The difference between polycystic kidney and renal cyst is different in etiology, distribution and prognosis. In terms of etiology, polycystic kidney is hereditary nephropathy, and renal cyst is acquired; in terms of distribution, polycystic kidney usually involves both kidneys, and renal cyst usually involves unilateral; in terms of prognosis, polycystic kidney mostly develops into uremia, and renal cyst has a better prognosis. 1. Polycystic kidney: it is usually a family dominant disease, which is congenital. Polycystic kidney may be related to renal tubular obstruction or localized dilatation of the kidneys; moreover, polycystic kidney is a disease of bilateral kidneys, and the patients with polycystic kidney will eventually suffer from renal failure in the late stage. 2. renal cysts: most of them are acquired, may be two kidneys are sporadic distribution, most of the cysts are relatively small, just occasionally appear in the localization of the two kidneys, renal cysts is a benign lesion, this part of the expansion of the renal tubules independently on the formation of a cyst, most of the single or scattered multiple, generally does not lead to renal failure. It is recommended that patients with polycystic kidneys or renal cysts go to regular hospitals in a timely manner and receive standardized treatment under the guidance of doctors to avoid delays.