The mixture simulation system of virtual model and real equipment requests for clear real-time characteristics to the virtual model.The running time of existing photon transmission model is too long to meet the real-time requirement of simulation system.For this problem

we described the photon transmission in the multi-layer flat-type media utilizing its group characteristics

and the photons in the received plane using Gaussian distribution

then got the photon distribution in receiving plane according to the results of total numbers and 63.2% energy radius.Experimental results show that the trends and values of this method are basically consistent with the standard Monte Carlo photon transmission model in the same simulation conditions

and this method delivers a substantial increase in speed which can meet the real-time requirements of general simulation system.