〔Abstract〕 Objective To investigate the related factors of elevated serum CA125 concentration in patients with idiopathic membranous nephropathy (IMN). Methods It was a single-center retrospective cross-sectional study.The patients with biopsyproven IMN who were hospitalized in Hechi People's Hospital from June 2013 to March 2021 were included. Patients were divided into two groups on the basis of serum CA125 concentrations: positive group ( > 35 U/ml), normal group ( ≤ 35 U/ml). Univariate and multivariate logistic regression were used to analyze the related factors of serum CA125 elevation in IMN patients. Results There were 295 patients included in this study. Compared with the normal group, patients in positive group exhibited higher levels of diastolic blood pressure, serum creatinine concentration, total cholesterol concentration, low density lipoprotein concentration, serum CA153 concentration ,urinary protein level as well as serum PLA2R antibody(all P < 0.05), and a lower level of serum albumin concentration, eGFR and serum IgG concentration (all P < 0.05), and had higher proportions of nephrotic syndrome ,serosal cavity effusion, Acute and Subacute Renal Insults, segmental glomerular sclerosis(all P < 0.05), Multivariate logistic regression analysis showed that Serosal effusion (OR 1.44, 95 % CI(1.04, 1.99), 0.0281) and low density lipoprotein concentration (OR 1.44, 95 % CI (1.04, 1.99), 0.0281) were independent risk factors for elevated serum CA125 of IMN. Conclusion In IMN patients ,the increaseof serum CA125 concentration was independently associated with serosal effusion and low density lipoprotein concentration.