China is the largest investor and second largest trade partner in Cambodia. With accumulated FDI of $2.4 billion, more than 3000 Chinese firms, ranging from large SOEs to SMEs are operating in all of the four pillar industries in Cambodia: garment, construction, agriculture and tourism. Based on resent field observations in Siam Reap, Phnom Penh, Sihanoukville, and Kampot, and interviews with officials of the Cambodian government, managers of Chinese firms, and representatives of local companies and communities, this article describes the strategies of the Chinese companies in Cambodia, their interaction with the local government and communities. It is found that the economic connection with China has improved infrastructure, created employment, and provided low cost consumer products in local market. These have positive impacts on the livelihood and social exchange of local communities. More directly, Chinese firms are engaging in CSR such as building road, providing electricity for local villages, free language class, and staff donation. In return, “friendliness of government and people” become one of the attractive aspects of Cambodia when Chinese firms make their location choice abroad. It is also suggested Chinese firms must be more alert for their social and environmental impacts and on the local communities and build them into the business strategy and company policy, as Cambodia is opened to more companies from Japan, Korea and other ASEAN countries.