Based on the thermal blooming effect theory for high-energy laser propagating in atmosphere, the vector model concept of thermal distortion parameter \boldsymbolN_\textD is put forward. Based on the vector model concept of thermal distortion parameter and the laser system simulation software EasyLaser, the scaling law between the centroid offset of laser beam farfield and the vector thermal distortion parameter is simulated and analyzed. The simulation results indicate that the centroid offset quantity is in direct proportion to the modulus of vector thermal distortion parameter \boldsymbolN_\textD , and the centroid offset direction is opposite to the direction of vector thermal distortion parameter \boldsymbolN_\textD . Based on the scaling law, by real-time measuring the atmosphreic parameters on laser beam propagation path, the beam deviation of laser system can be conveniently estimated in practical application.