Abstract: Objective:To investigate and analyze the motivation of participating voluntary service in medical undergraduates.Methods:Three hundred medical college students were investigated using the voluntary motivation scale by the method of cluster sampling.Results:Among 300 medical students,159 students participated the voluntary service activities(86.3%),and 41 students did not participate in the voluntary service activities(13.7%).The scores of the value expression,career,social interaction,learning understanding,self enhancement and volunteer motivation in grade 3 students were higher than those in Grade 1 students(P<0.01).The total scores of the self-protection,social interaction and voluntary motivation in male students were higher than those in female students(P<0.05 to P<0.01).After entering the university,the score of the social interaction in good students was higher than that in medium students(P<0.05).The scores of the value expression,career,social interaction,learning understanding,self enhancement and volunteer motivation in rural students were higher than those in county students(P<0.05 to P<0.01).The scores of the learning,understanding and self enhancement in rural students were significantly higher than those in town students(P<0.01).The differences of the scores of the monthly income in each dimension and voluntary motivation were not statistically significant(P>0.05).Among 6 dimensions of volunteer motivation scale of medical students,the scores of learning understanding,self enhancement,value expression,career,social interaction and self-protection were 5.117,5.059,5.048,4.910,4.420 and 4.339 points,respectively,and the average score of which was 4 points.Conclusions:The diversification of the voluntary service motivation and using own professional advantage in medical students are the main choice of volunteer service.The diversification of participating volunteer service can enhance the ability of certain aspects and meet some needs of students.Meet the voluntary service motivation can also encourage students to participate the volunteer service activities.