A new multi-physics simulation model for quasi-three-level slab lasers is reported in the paper.Based on the absorption characteristics of the pump light,the thermodynamics and the gain characteristics of the laser,the model complements the traditional quasi-three-level calculation model.The model considers the influence of laser generation on the internal physical field of the gain medium,and gives a new convergence simulation method based on the coupling relationship between multiple physical fields.This model is suitable for single-ended and double-ended pumped laser resonators and amplifiers.