”Nephrotic syndrome is a common kidney disease in clinical practice, and early diagnosis and treatment play an important role in the treatment of the disease and the recovery of the patient’s body. In order to avoid the delay of patients’ disease and to improve the attention of patients to nephrotic syndrome. Now I will briefly talk about nephrotic syndrome (NS).” (Editor/Shiyuan Liu) Nephrotic syndrome (NS), referred to as nephrotic syndrome, is a group of clinical syndromes caused by a large amount of proteinuria and its causes due to multiple etiologies. The clinical manifestations have common features: (1) massive proteinuria, ≥3.5g/d; (2) hypoproteinemia, serum albumin ≤30g/L; (3) edema; and (4) hyperlipidemia. Among them, especially the first two are the most important and necessary conditions. Nephrotic syndrome is divided into primary nephrotic syndrome and secondary nephrotic syndrome according to its etiology. 1. Diagnosis Firstly, according to the urine protein quantification and plasma albumin concentration, with reference to edema and hyperlipidemia, we can determine whether the diagnostic criteria of nephrotic syndrome are met. Secondly, secondary causes (infections, drugs, toxins, allergies, tumors, systemic diseases, metabolic diseases and hereditary diseases) must be excluded before primary nephrotic syndrome can be diagnosed. If necessary, renal biopsy is required to make a clinicopathological diagnosis based on a comprehensive clinical and pathological analysis. Primary nephrotic syndrome is classified according to its pathological features: ① Microscopic lesions (MCD). It is the most common pathological type of pediatric nephrotic syndrome. ②Tethered proliferative nephritis (MSPGN). (iii) Focal segmental glomerulosclerosis (FSGS). ④Membranous nephropathy (MN). 2. Differential diagnosis (1) Diabetic nephropathy: seen in those with long duration of diabetes. It starts with microproteinuria, gradually develops into massive proteinuria, and later affects renal function and develops renal failure. According to the medical history, clinical manifestations, diabetic fundus lesions are helpful for the diagnosis, but there are still some patients with diabetes combined with primary nephropathy, then need a kidney biopsy to clarify the diagnosis. (2) renal amyloidosis: the kidney is one of the most common and earliest organs involved in amyloidosis, with clinical manifestations of massive proteinuria, progressive development of renal failure, and a poor prognosis, divided into primary or secondary (chronic infectious disease or rheumatoid arthritis, familial onset, multiple myeloma, etc.) amyloid lesions, which can be combined with cardiac hypertrophy, gastrointestinal disorders, giant tongue, liver and spleen. The renal pathology is a reliable means to diagnose amyloidosis. (3) Secondary to lymphoma: solid tumors and hematologic tumors can cause nephrotic syndrome manifestations, and in elderly patients, more attention should be paid to exclude such factors, and the differential diagnosis is facilitated by the tumor history and clinical manifestations. Combined with clinical experience, the following points should be noted for the diagnosis of nephrotic syndrome: ① Primary nephrotic syndrome with combined diabetes mellitus. In clinical practice, nephrologists generally give priority to diabetic nephropathy in patients who have diabetes mellitus with massive proteinuria, but in fact, there are still some patients with massive proteinuria not entirely caused by diabetic kidney damage, but combined with primary nephrotic syndrome. Since primary nephrotic syndrome often requires hormone therapy, and diabetic nephropathy hormone efficacy is often not obvious, but on the contrary, it tends to lead to abnormal blood sugar and lipid metabolism. For this condition, we should pay attention to understand the actual duration of diabetes, because the time of finding diabetes is not equal to the actual time of having diabetes, diabetic nephropathy to the stage of massive proteinuria, often the duration of the disease then nearly 10 years or more, short-term diabetes usually does not cause massive proteinuria. If the exact condition is not available, then the duration of the disease can also be indirectly determined based on the level of blood sugar control, whether the blood sugar can be controlled with medication, the condition of other complications such as neurological and vascular conditions, especially diabetic fundus changes, which provide a basis for diagnosis. If necessary, a renal biopsy is required. ②Nephrotic syndrome with early onset in young age. The pathological type is more likely to be microscopic lesion type, which can be treated directly with hormone without kidney biopsy first. If the effect is not good or shows hormone dependence, further renal biopsy will be performed to clarify the diagnosis.