This paper analyzes the culture conflicts between two merged IT departments from two banks and how they resolve them. The integration of divergent cultures is crucial to maintain the performance of merged organizations. This paper examines post-merger IT integration of a Taiwan's financial holding company which merged a government owned bank with its banking business, and argues that the understanding of IT culture conflict between two merged departments can contribute to effective post-merger IT integration. This paper identifies three types of IT culture conflict occurring in IT integration, and then discusses how to resolve IT culture conflict in post-merger IT integration. We assert that IT department can resume the productivity once IT culture conflict can be identified and resolved even IT infrastructure and processes of merging organizations are incompatible.