It is commonly assumed that MNCs should be equally socially responsible in both their home country and host counties. However, based on the cases of Chinese market, the paper finds that the CSR performance of MNCs in the host country may differ from that in their home countries. The main reasons for the differences include their internal cost pressure, difficulty in internal control, defects in governmental supervision, and differences in legal or cultural environment, etc. It is thus suggested that countermeasures should be taken to handle the issue effectively, such as perfecting related regulations, establishing mechanisms for international cooperation, enhancing supervision and law enforcement, as well as strengthening media transparency.