In order to solve the problem of limited simulation of rocket movement, a method based on computational fluid dynamics(CFD) numerical simulation is proposed, applying overlapping grid technology to simulate the drift motion during rocket launch. The variation of thermal and mechanical environment around the umbilical tower under the condition of rocket drift is studied. The numerical simulation results considering the rocket drift motion are given, and the influence of the rocket lateral motion on the surface temperature and jet pressure of the umbilical tower is analyzed, and the variation of the time history curve of different measuring points on the surface of the umbilical tower is revealed. The results show that the pressure of the umbilical tower jet decreases along the height, the pressure and temperature of the bottom jet are the highest, and the pressure of the bottom jet increases with the increase of the take-off height and drift of the rocket; The pressure of the measuring point at the bottom of the umbilical tower reaches the peak value when the rocket rises 20 m and the drift is 3.16 m, and the maximum pressure can reach 0.5 MPa.