Due to increasingly global competition, many companies find ways to increase competitiveness, revenues and operation scope. When multinational companies establish foreign subsidiaries, parent companies use expatriates to manage and control subsidiaries. Therefore, expatriates play an important role on the successful operation of overseas subsidiaries. Because of the different environment and culture, most of expatriates are unable to adapt to the host country environment. Consequently, expatriate adjustment is an important factor contributing to successful foreign assignment. To avoid expatriate failure, multinational companies should find determinants of overseas adjustment. It has become a managerial issue that multinational companies must concern in the internationalization process. The study explores impacts of job autonomy, acculturation and organizational support on expatriate adjustment; and understands the relationship between expatriate adjustment and expatriate performance; moreover, examines the mediating effect of expatriate adjustment. By related literature review, we establish the research framework and propose hypothesis. The participants of the study were 111 expatriates in foreign subsidiaries which simultaneously collected by paper, internet and electronic questionnaires. The valid return rate was 27.8%. The empirical results are: (1) Job autonomy has positive influence on expatriate adjustment; (2) acculturation has partial and positive effect on expatriate adjustment; (3) organizational support has partial and positive influence on expatriate adjustment; (4)expatriate adjustment has partial influence on expatriate performance; (5) expatriate adjustment play a partial mediating role between acculturation and expatriate performance. Based on findings, this study proposes further discussions and suggestions for multinational companies and further research.