Objective　To investigate the effect of taking medical students as standardized pa-tients（SSP） on problem based learning（PBL） teaching in clerkship. Methods　Totally 161 students（grade 2008） selected from clinical medical department was divided into PBL group（n=81） and lecture-based learning（LBL） group（n=80）. SSP was introduced into PBL teaching and LBL group was taught by LBL. After the clerkship， theory test was conducted in two groups and questionnaire was given to LBL group. Statistical analyses were conducted by SPSS 13.0， measurement data were ana-lyzed by t test and enumeration data were described by frequency and constituent ratio. Results　The-ory test results showed that the average score of medical record analysis was （37.35±5.95） in PBL group， much higher than （33.25±4.89） in LBL group（P＝0.０01）；the total score was （71.20±8.67） in PBL group， much higher than that of （67.79±9.87） in LBL group（P＝0.0１８） as well. The average scores of choice question in 2 groups were （33.85±5.05） and （34.24±6.87）， without significant differences（P ＝0.６5８）. The constituent ratio of answer ‘OK’ regarding 10 entries in questionnaire was more than 75%. The constituent ratio of answer ‘OK’ regarding 3 entries（SSP matching degree， SSP without implied language or action， stimulating the learning interest） was more than 90%. Conclusions　Introducing SSP PBL teaching can improve students' ability of clinical analysis and problem solving but not so effective for the basic theoretical knowledge grasp. SSP could replace standardized patients in PBL teaching.