Based on the diffraction theory, the specific beam structure and optics wavefront data of the SG-II updated laser facility, a calculation model of the wavefront propagation for the facility is established. Using the calculation model some important data for design and operation of the facility are gained, including the corrected profile of deformed mirror, dynamic wavefront aberration of the amplifier, wavefront aberration and focus of the spatial filter, which are difficult to get by experiment. Analysis and comparison under three types of conventional operation, such as static propagation, static propagation and large energy shot with adaptive wavefront correction, indicates that the theoretical results are in good agreement with the experimental data. And the wavefront propagation of large energy shot in absence of the adaptive wavefront correction is calculated. The wavefront propagation model can be used to improve design of the related devices, optimize operation and control mode of the laser facility, and improve wavefront quality of the output laser beam.