Objective To investigate the feasibility and effectiveness of online simulation on clinical reasoning training. Methods Online clinical reasoning training was implemented through tencent Meeting platform for graduate medical students. Associated medical knowledge was arranged before the class for preparation. In the online classroom, history taking, physical examination, lab or imaging examination prescription and explaining, and decision making of diagnosis and treatment were performed by the students, who played as physician,while the trainer as standardized patient.A briefing was taken after the procedures. Process-evaluation was made and questionnaires were distributed to inquire of satisfaction of students and barriers of undertake online class for teachers. Results The class was successfully performed without difficulty. The students were interested in online training and highly involved in discussion. 70.0% of students interacted with the trainer without delay,which means they were concentrated on the class on the other end of computer or smartphone. 100% students were satisfied with the class and expected the similar class. Conclusions Online simulation on clinical reasoning training is feasible and effective with high satisfaction, which is valuable in distant education or in some special context.