In recent years，the gap is widening between urban and rural residents’ income, accompanied with the widening gap between urban and rural residents’ human capital investment., which have interaction each other in the traditional theory. In Guizhou province, whether the traditional theory was tested in real life is worth to verify by quantitative and qualitative method. The results discover that the gap of the human capital investment has none effect on the one of income between urban and rural residents. However, the gap of income can change the one of human capital investment directly. In the end, some suggests were given.