Renal insufficiency refers to the reduced function of the kidneys, resulting in disorders in the body’s excretion of metabolic wastes and the regulation of water-electrolyte and acid-base balance. It can be categorized into acute renal insufficiency and chronic renal insufficiency. Under normal circumstances, the kidneys have the functions of regulating body fluids and blood pressure, regulating blood chemistry and removing organic wastes. When kidney function is impaired, abnormalities in the above functions will occur. Renal diseases and extra-renal diseases can cause renal insufficiency, such as acute and chronic glomerulonephritis, shock, heart failure, hypertension, diabetes mellitus and so on. Acute renal insufficiency refers to the clinical syndrome caused by the rapid decline of renal function in a short period of time, which is manifested by the decrease of glomerular filtration rate, accompanied by the retention of nitrogen products such as creatinine, urea nitrogen, etc., and the disturbance of water, electrolyte, and acid-base balance, and in severe cases, the emergence of multi-system complications. Chronic renal insufficiency is the common outcome of various chronic kidney diseases that continue to progress to advanced stages. It is a clinical syndrome characterized by metabolite retention, water, electrolyte and acid-base balance disorders and systemic symptoms, and requires renal replacement therapy when it develops into end stage. It is recommended that patients with renal insufficiency should seek medical treatment as soon as possible and be actively treated under the guidance of physicians.