Aiming at the problems that it is difficult to make priority evaluation of maintenance support force dispatching with traditional methods, Monte Carlo simulation method is put forward to determine the priority of each maintenance support force dispatching object. The factors that influence decision of maintenance support force selecting plan are analyzed, and the evaluation index is introduced. The mathematical description of maintenance support force selecting in wartime is developed and the model of support force selecting is built on the basis of the consideration of priority. Practical example shows that the model is objective, accurate and effective. This research result can offer a theoretical guide for decision of maintenance support force selecting in wartime.