Abstract: The application of IaaS cloud service in large firms is studied and its impacts on firm performance are investigated Based on the theoretical and qualitative studies in this area, a field survey within a sample of large firms is conducted first and relevant data of their IaaS cloud services are collected Then from the perspective of business process, the mechanisms regarding how the IaaS cloud services impact firm performance are analyzed In the end, several managerial recommendations are put forward, including: ① firms should focus on developing and building integrated cloud computing capacity; ② the tight connection between cloud computing and business process doesn’t necessarily lead to better collaboration; ③ the correct and appropriate collaboration between cloud computing and business process is more important than the tightness of their matching

Key words: IaaS cloud service, IT capacity, business process, firm performance