Abstract: Cosmic ray muon radiography which has a good penetrability and sensitivity to high-Z materials is an effective way for detecting shielded nuclear materials.Reconstruction algorithm is the key point of this technique.Now,MLS-EM reconstruction algorithm is a better one than other existing radiographic methods.However,its reconstruction time is too long to let it be used into a real detective system.Because of that,based on the characteristics of the muon radiography system,this paper proposed a good method to accelerate MLS-EM.It used the POCA algorithm as the initial value of the EM,and then accelerated the algorithm using the function of the OS.Finially,the simulation experiments demonstrated that this method could effectively accelerate MLS-EM.Therefore,it played a significant role to do a further step to let the technique of cosmic muon radiography into our real life.