The six-degree-of-freedom motion of the sea launch ship will cause the transfer and rotation of the blast deflector installed on the ship, adversely affecting the discharge of the launch vehicle's gas jet. To study the effect of the blast deflector’s motion on the rocket wake flow field, this paper establishes a certain type of carrier rocket tail nozzle and blast deflector combination model. The CFD software Fluent was used based on the Realizable k-turbulence model and the second-order windward format to establish a transient numerical simulation model of the wake flow field. And the rocket wake flow field of the velocity, pressure and temperature were presented under the blast deflector translational and rotational movement. The results show that the horizontal movement of the blast deflector caused by the ship will significantly increase the total force on the flow surface, with a maximum increase of 70% under some operating conditions. As the blast deflector’s rotation angle increases, the total pressure value at the deflector surface increases. The specific combination of motion will cause local high temperature and pressure in the blast deflector. The analysis results in this study can be used as a reference for the configuration and thermal protection of the sea launch carrier rocket blast deflector.