Financial and investment are two parts of the corporate finance. After M M and Markowitz's celebrated works, the research has been deeply proceeded. However, most of the research treated these two aspects separately, ignoring the mutual influence between them in a firm. In our paper, we give a general description and analysis of the study on capital structure theory and investment decsion making, and make some comments on the existing papers. At last, some thought of the joint determination of capital structure and investment return and risk are also presented