The so-called membranous nephropathy is a diagnostic term for the pathomorphology of chronic glomerulonephritis. It is the deposition of immune complexes on the epithelial side of the patient’s glomerular capillary collaterals, which can cause thickening of the basement membrane and also damage to the patient’s podocytes, which leads to disruption of the integrity of the glomerular filtration barrier and the appearance of proteinuria, which is usually not accompanied by proliferation of glomerular lamina propria in the patient. Membranous nephropathy is divided into four periods according to the patient’s pathological changes, which must be examined by electron microscopy. The second stage of membranous nephropathy refers to the increase of dense material on the epithelial side of the glomerulus, that is, the increase of immune complexes, and the thickening of the basement membrane, which protrudes to the epithelial side to form a pegged protrusion, but there is no obvious stratification of the basement membrane in this stage.