In general, all factors that can cause glomerular filtration membrane damage can lead to nephrotic syndrome. The diagnosis of the former depends mainly on the exclusion of secondary nephrotic syndrome. The cause of primary nephrotic syndrome is unknown, but the findings suggest that immune mechanisms, especially changes in cellular immunity, may be involved in the development of the syndrome, as well as disorders of lipid metabolism, changes in coagulation factors, and large amounts of proteinuria. The common causes of secondary nephrotic syndrome are as follows. 1, infection bacterial infection, seen in streptococcal post-infection nephritis, bacterial endocarditis, shunt nephritis, leprosy, syphilis, tuberculosis, chronic pyelonephritis with reflux nephropathy; viral infection seen in hepatitis B, cytomegalovirus, infectious mononucleosis, human immunodeficiency virus; parasitic infection seen in Plasmodium, toxoplasmosis, helminths, schistosomiasis, filariasis. 2, drugs or poisoning, allergies Organic or inorganic mercury, organic gold and silver, penicillamine, diacetylmorphine, propoxur, non-steroidal anti-inflammatory drugs, trimethoprim and other drugs; bee stings, snake venom; pollen, vaccines, antitoxins and other allergies. 3.Tumors Tumors of lung, stomach, colon, breast, ovary, thyroid, leukemia and lymphoma, Willm’s tumor, etc. 4.Systemic diseases Systemic lupus erythematosus, mixed connective tissue disease, dermatomyositis, Schegren’s syndrome, allergic purpura, amyloidosis, etc. 5.Metabolic diseases Diabetes mellitus, thyroid disease. 6.Hereditary diseases Congenital nephrotic syndrome, Alport syndrome, Fabry disease, sickle cell anemia, nail – bin bone syndrome, lipodystrophy, familial renal syndrome, etc. 7, other Eclampsia, chronic rejection of transplanted kidney, malignant nephrosclerosis, renal artery stenosis, etc. Among the secondary nephrotic syndromes in China, systemic lupus erythematosus, diabetic nephropathy and allergic purpura are the most common. The focus here is on primary nephrotic syndrome. The common pathological histological changes of primary nephrotic syndrome in pediatric patients are predominantly microscopic lesion type. In adults, focal segmental nephritis, membranous nephropathy, and microscopic lesions predominate. In recent years, the etiology of adult nephrotic syndrome has changed significantly, with membranous nephropathy being the most common cause between 1970 and 1980, followed by microscopic nephropathy and focal segmental glomerulosclerosis. It was thought that focal segmental glomerulosclerosis should not occur in nephrotic syndrome, but clinical renal biopsy confirmed that focal segmental glomerulosclerosis surpassed membranous nephropathy. mark et al. reported that membranous nephropathy accounted for 36%, microscopic lesions for 23%, and focal segmental sclerosis (FSGS) for 15% from 1976 to 1979. In contrast, FSGS was already the main cause of nephrotic syndrome in 1995-1997, accounting for 35%. They also found that in the 1995-1997 group in blacks with nephrotic syndrome FSGS accounted for 50% and 67% were under 45 years of age. There was a decreasing trend in microscopic lesion nephrotic syndrome and a decreasing trend in membranoproliferative nephritis, while thylakoid IgA nephropathy was increasing year by year. Data show that AL amyloid nephropathy in 10% of cases aged 44 years or older, but multiple myeloma and paraglobulinemia could not be confirmed.