The size and effectiveness of sovereign wealth fund (SWF) continuously grows and impacts on global capital market. The investment purpose of SWF may be based on political consideration rather than only commercial interest so that it raises other countries' concern about national security. This paper analyses and compares four kinds of sovereign wealth investment, and the similarities and differences among SWF, hedge fund and private equity fund. It explains the current development of SWF and analyses the future supervision and development of SWF.