This study discusses several issues which are very important in worldwide mergers and acquisitions, such as cultural differences, culture clashes, operating results and financial quality. A case of SAIC Motor's acquisition of Ssangyong Motor is examined. For this study, 20 financial ratios are used to calculate the financial quality of SAIC in the post-acquisition integration. The result shows that cultural differences possibly have a negative effect on post-acquisition integration and cultural clashes are the root cause of the financial quality plummet. The suggestions are also provided that top managers should pay much more attention to the negative effects of cultural clashes and strengthen cultural integration.