Objective To investigate expression of YAP in idiopathic membranous nephropathy (IMN). Methods Expression of YAP protein in IMN patients and normal renal tissues was detected by immunohistochemistry. An injury model of the human podocyte line MPC5 was established in vitro with C5b-9. Expression of YAP protein in podocytes was detected by Western blot. siRNA transient transfection was used to silence YAP gene expression in podocytes. The transfection efficiency was assessed by qRT-PCR and Western blot. Podocytes were divided into four groups: control, C5b- 9, C5b-9+si-NC and C5b-9+si-YAP groups. A CCK-8 assay was used to assess the proliferation activity, annexin V-FITC double staining combined with flow cytometry was used to assess apoptosis, DCFH-DA staining was used to detect the content of reactive oxygen species (ROS). Western blot was used to measure the apoptosis rate. The expression of podocyte marker protein nephrin, WT1, tight junction protein ZO-1, phenotype transition protein snail and fibronectin was detected by Western blot. Results Compared with normal renal tissue, the expression of YAP in IMN was increased significantly (P< 0.05). With prolongation of the C5b-9 stimulation time, the expression level of YAP protein was increased in podocytes (P< 0.05). After si-YAP transfection, the mRNA and protein levels of YAP in podocytes were decreased significantly (P<0.05). Compared with the control group, cell proliferation in C5b-9, C5b-9+si-NC and C5b-9+si-YAP groups was decreased significantly, while the apoptosis rate and ROS content were increased significantly ( P< 0.05). However, compared with C5b-9 and C5b-9+si-NC groups, cell proliferation in the C5b-9+si-YAP group was increased significantly and the ROS content in cells was decreased significantly (P<0.05). Expression of nephrin, WT1 and ZO-1 in C5b-9, C5b-9+ si-NC and C5b-9 + si-YAP groups was significantly lower than that in the control group ( P< 0.05). Compared with C5b-9 and C5b-9+si-NC groups, the protein expression of nephrin, WT1 and ZO-1 in the C5b-9+si-YAP group was increased significantly, while the protein expression of Snail and fibronectin was decreased significantly ( P< 0.05). Conclusions This study showed that YAP protein expression in glomeruli of IMN patients is significantly increased and silencing YAP gene expression in podocytes significantly improves C5b-9-damaged induced functions and inhibits apoptosis.