Objective To investigate the value of ratio of luteinizing hormone (LH) to folliclestimulating hormone (FSH) in diagnosis of polycystic ovarian syndrome (PCOS) among women with ploycystic ovary (PCO) and to compare the difference of the diagnostic criteria between the Rotterdam Consensus and the Committee for Reproductive and Endocrine in Japan Society of Obstetrics and Gynecology.Methods By means of transvaginal Doppler ultrasound, 195 women with PCO were diagnosed in Nanfang Hospital of Reproductive Medicine Center and compare difference of multiple clinical indexes according to Rotterdam consensus and Japan consensus respectively. In the mean time, the ratio of LH/FSH, the level of LH, testosterone (T) and recevier operating characteristic (ROC) curve were explored to on the value of diagnosis of PCOS. Results By Rotterdam consensus, 144 women were diagnosed with PCOS and 51 women were non-PCOS, while 111 were identified as PCOS and 84 were non-PCOS according to Japan consensus. LH/FSH in PCOS and non-PCOS were 1.59 ±0. 84 and 0. 85 ±0. 47 respectively when based on Rotterdam consensus, and this ratio were 1.87 ± 0. 76 in PCOS and 0. 78 ± 0. 39 in non-PCOS based on Japan consensus. When using LH/FSH to diagnosis PCOS by Rotterdam consensus and Japan consensus,areas under ROC curve are 0. 786 and 0. 942, respectively. Conclusions The ratio of LH/FSH ≥ 1 provide the significant value in the diagnosis of PCOS. The criteria of the Committee for Reproductive and Endocrine in Japan Society of Obstetrics and Gynecology is more suitable for Chinese patients.