Hong Kong is the most important destination when Mainland China's enterprises launch outward foeign direct investment (OFDI). The purpose of this article attempts to analyze and discuss investment motives of Chinese firms by virtue of macroeconomic data and case studies. At the macroeconomic level, the main goal of China is to smooth the process of the return Hong Kong to China, maintain Hong Kong's subtainable prosperity during the transition, and balance the macroeconomic disequilibrium. At the microeconomic level, the case studies indicate that investment motives of Chinese firms include political consideration, raising funds, market-seeking, strategic resource-seeking and capital-fleeing etc.