Abstract: It is significant for both urban economy and rural economy when rural labors migrate to cities. In this paper，by economic theory analysis，the authors brought forward the hypothesis，positive correlativity between the economic variables and rural labors. These economic variables included grain yield，farm-oriented mechanical industry， building industry，tertiary industry，value of export and import and the rate of urbanizing. With the method of principle component analysis，it could overcome the together linear among these economics variables. It was demonstrated that rural labor forces had some relevance to these economic variables by the regression model，it matched very well with the real data. The research illustrated that all the industrial development，including first，secondary and tertiary industry development，contributed to the migrant labor scale. The role played by inner industry was different. Development trade of export and import and raising urbanization level also had push effects on migrant of rural labors.