Membranous nephropathy is a pathological type of primary glomerulonephritis, which usually manifests as nephrotic syndrome. Membranous nephropathy is divided into idiopathic membranous nephropathy and secondary membranous nephropathy, where the common causes of secondary membranous nephropathy include various malignancies, lupus nephritis, and hepatitis B-associated nephropathy. The etiology of primary membranous nephropathy is not particularly clear at present. It may be due to various causes of IGA deposition under the glomerular epithelial cells, which causes complement activation, thus damaging the glomerular filtration membrane and causing a large amount of protein to leak out from the urine, thus damaging the kidney. The diagnosis of membranous nephropathy depends on pathological examination. After the diagnosis of membranous nephropathy is confirmed, the application of glucocorticoid therapy alone is usually ineffective, and combined immunosuppressive therapy is required.