The dynamic characteristic of transmission test platform has a major impact on the accuracy and reliability of test results for precision reducers. A self-developed multi-axis precision transmission test platform is taken as the research object, and a calculating method of the joint part stiffness of cross roller linear guide way is proposed based on Hertz Contact theory. According to the actual test working state of cross axis reducer, spring unit is applied to simulate the contact characteristic of guide way joint part and the dynamic model of test platform at limit position is established. And then, the theoretical modal analysis is carried out by finite element method and the natural frequencies of the first 4 steps and modal shapes of the platform are obtained. Finally, the dynamic characteristic of test platform is verified by sample testing. The maximum vibration velocity of platform under actual working state is 0.478 mm/s. The results show that this new transmission test platform has excellent dynamic performance and it can satisfy the vibration criterion of precision equipments.