Abstract: Changing jobs occurs frequently in the rural migrant labor market. The income effect resulting from the job mobility reflects the matching efficiency between the training background or work experience of human capital and the job responsibility requirements. Based on Rural Urban Migration in China (RUMIC) data, and applying Endogenous switching regression model, this paper examined the impacts of job mobility on the returns of human capital and also explored the heterogeneity of the returns of common human capital and specific human capital. Results show that 1) changing jobs were prevalent for migrant workers: 34.5% of them have job changing experience; 2) job mobility can increase the return of common human capital and will decrease the return of specific human capital; 3) the return to education of migrant workers with job changing experience is greater than those who without: the changer’s return to education increased by 3.18 percent, while the stayer’s return to education only increased by 2.25 percent; 4) the training benefits of migrant workers without job changing experience were higher than those with job changing experience (10.11 percent VS 8.36 percent); and 5) the return to work experience of workers without job changing experience was higher than that of the workers with job changing experience. This research illustrated job mobility is not conducive to the income increase and employment quality improvement of migrant workers. Based on the findings of this research, migrant workers should be encouraged to change jobs moderately in order to enhance the quality of employment.