Cultural difference is one of the main reasons why current offshore outsourcing deals fail or experience problems. This paper illustrates the influence mechanism of cultural differences on the offshore service outsourcing，analyzes the main problems in everyday outsourcing relations, and develops a set of evaluation criteria for cultural differences in offshore service outsourcing. The importance of each cultural criterion is ranked through an empirical survey. It is found that the most attention should be paid to cultural compatibility and internationalization when choosing outsourcing location, especially the two criteria of cultural compatibility: common language and communication. Therefore, in order to promote the cultural integration of offshore service outsourcing, this paper offers suggestions of attaching importance to cultural differences in outsourcing decision, improving English level, strengthening communication, promoting internationalization as well as providing intercultural training.