With the development of globalization, increasingly more companies began to use worldwide resources to do product or service research and development. Multinational corporations (MNC) became to more rely on their subunits that located in different countries to conduct innovations. As a result, keep a good knowledge transfer between headquarter and subunits or among peer subunits is crucial for MNC to operate R & D activities. This study explores the relationship between knowledge transfer and R & D operations through two knowledge transfer mechanisms and three categories of R & D configurations.   By applying the qualitative strategy with a focus on four case companies (three are from Sweden, one is from China), we conduct a cross case analysis and the result shows that both expatriate management policy and communication frequency are very important knowledge transfer mechanisms for MNC to keep a good knowledge transfer in global R & D operations. In terms of expatriate management policy, it is very important for MNC sending engineers from headquarter to subunits or between peer subunits in order to transfer technology knowledge and facilitate R & D operations. Moreover, send top managers from headquarter to subunits could also help transfer process knowledge and keep overall control of subunits. In terms of communication frequency, if MNC employs a concentrated development in headquarter (or R & D center), it is very important to maintain a frequent communication between headquarter and subunits so as to keep a smooth knowledge transfer between them. And if MNC applies a dispersed research and development configuration, keep a frequent communication between peer subunits is crucial. In addition, this study also found certain connections between innovation process and R & D configurations.