To increase farmers' income and narrow the income gap between urban and rural residents in China, it is an important way to realize common prosperity. However, because of the slowing-down increase in farmers' income, some schemes should be taken to broaden income sources, tap latent potentialities and cultivate new points of income growth.

With the development of industrialization and urbanization, non-farm income that exceeds agriculture income has mainly accounted for the proportion of farmers' income. Due to Chinese household registration system, most farmers devote themselves to part-time business to maximize income. How does the business behavior have the influence on non-agricultural income? Based on a literature review of part-time business behavior and non-farm wage income, it could be found that most studies focus on part-time business or non-farm wage income, and have no systematic review of their relationship. Therefore, this paper investigates the effect of farmers' part-time behavior on non-farm wage income, and aims to perfect existing research and provide further research ideas.

In order to achieve above objectives, firstly, this paper puts forward two following hypotheses:firstly, part-time business behavior would not only reduce farmers' non-agricultural income, but also cut down hourly wage level. Secondly, individual characteristics, career choices and part-time business behavior would be the factors that play the important roles in farmers' non-farm wage income. What's more, the part-time business behavior is the main factor that would make wage income gap between farmers with combined occupations and farmers who only are busy with non-agricultural jobs. Then according to China Family Panel Studies (CFPS) in 2012, this paper empirically studies these effects by using treatment effect model and income decomposition method.

Results are showed that part-time business would significantly reduce farmers' wage income and actual hourly wages. What's more, it shows that the discrimination effect caused by part-time behavior is the main reason for non-farm income gap between farmers with combined occupations and ones who only are busy with non-agricultural jobs. Therefore, the implementation of policies to promote farmers' income should be aimed at improving policy accuracy, such as striving to break institutional constraints represented by dividing the household registration system to encourage farmers transferring to non-agricultural sectors, and deepening agricultural supply-side reform to improve the land property income and increase farmers' gross income.