Now our country has reached the top of the world for the level of bridge construction, for example, the Hong Kong-Zhuhai-Macao Bridge, the longest cross-sea bridge in the world, and Guizhou Guanling Bridge, the largest steel girder suspension bridge in China, etc. However, the safety monitoring of the bridge in the use stage can not be ignored. There are many methods to monitor the safety of the bridge, but the monitoring of the very large span bridge using conventional methods are difficult. In this paper, IBIS-S microwave interferometry technology is used to test the safety monitoring of the very large span bridge, and the deformation of the bridge is analyzed through the microwave signal sent by radar, this can not only be used for non-contact measurement, but also for real-time dynamic monitoring of the bridge. The experiment takes Jinan Huanghe Fenghuang Bridge as an example，the instrument is set up on the south bank of the bridge at a horizontal Angle of 5°, the deflection of the bridge is monitored with three different sampling frequencies of 60HZ, 40HZ and 20HZ. Results show that the microwave interferometer radar can monitor the deformation of the bridge, and the maximum deformation reaches 215.14mm,according to the General Code for the Design of Highway Bridges and culverts, the deformation of the bridge is within the safe range; IBIS-S technology can be used for dynamic monitoring, and it is easy to operate and has high sampling frequency to measure the dynamic deformation of Bridges quickly and efficiently.