From Guofa document No.43 in 2014 to Caiyu document No.50 in 2017，it is clear that “the government financing function of the financing platform company should be stripped” and “the financing platform company should be transformed into a state-owned enterprise with market operation as soon as possible”. The transformation of the city investment company is the general trend. However，the transformation of city investment is far from simply withdrawing from the list of “financing platform companies”. Only by promoting business transformation can city investment companies truly achieve market-oriented operation. Firstly，this paper analyses the business development status of CIC，and then introduces the new business direction of CIC，such as new infrastructure construction，pension industry and environmental protection industry. Finally，combining with the exploration and practice of business transformation of various city investment companies，this paper proposes that city investment companies can develop new business by extending the industrial chain of “urban construction and operation”，establishing mixed ownership enterprises，and giving full play to the role of industry investment guidance.