The laser induced collisional energy treasfer (LICET) is Ba Sr system in suggested, which satisfies the condition |ω21|》|ω43|. And the results of numerical calculations of the Ba Sr system are obtained from the four level model and the conventional three level model respectively. The results of numerical calculations in Ba Sr further prove the theoretical prediction that the four level model can be simplified as a conventional three level model if the condition |ω21|》|ω43| is satisfied.