Scientific and exact evaluation for equipment maintenance support system is important for improving the shortage of system and enhancing support effectiveness. In fact, because of the uncertain information in evaluation, it is difficult to obtain exact conclusion. To counter the shortage about the uncertainty in current evaluation methods, an evaluation model based on degree of grey incidence and evidence theory is proposed. Through establishing the evaluation index system and calculating degree of grey incidence between the system condition gained with different methods and the evaluation grade of system, the basic probability assignments for evaluation grade are derived, and then the combination rule of evidence theory is used to fuse the evaluation grade in different methods for evaluation conclusion. The practical calculation result shows that the model is effective.