Functional model of interventional surgery robot system is obtained based on the analysis of interventional surgery needs. Combining the original design results, functional models are further analyzed. An innovative design method of interventional surgery robot based on TRIZ theory is proposed to simply the mechanism and perfect function. The problem model is defined by using TRIZ method. System tailoring strategy based on functional model and invention principle based on conflict resolution theory are combined for solving the design problem. Then, the new structural scheme is given based on the above analyses. The synthesized structural scheme has been greatly simplified. Finally, the TRIZ theory is used to evaluate the innovative design scheme. It is concluded that the improvement of the new scheme relative to the original scheme follows the evolutionary mode of expansion and simplification of the technical system, and conforms to the evolutionary rule of the technical system.