Transnational R&D investment belongs to FDI,and is the higher form of FDI for it is the transnational transfer of founding,technology,management notion and so on.The technology spillover of transnatinal R&D has resenblerance with common FDI in four spillover ways of demonstration,competition,talent flow and cooperation.However the technology spillovers of transnatinal R&D also has different characters and inherent regulations.The article sets up the theoretical analysis frame of technical spillover effect of the transnational R&D investment from three dimensions such as spillover characteristic,spillover way and influence factor of the spillover and so on,attempting to provide the effective policy-making basis for judging the technical spillover effect of the transnational R&D investment and implementing the multi-level policy-making.