In order to reasonably determine the best time for preventive maintenance of cement concrete pavement at military airports, the relationship between the pavement damage index and IRI is established on the basis of the analysis of the existing highway and airport pavement performance model. The decision model of preventive maintenance time for cement concrete pavement of military airport is obtained, combined with the pavement damage index decay model and the damage indexIRI relationship. Based on the current situation that our army still mainly uses the threemeter ruler to test the roughness and a large amount of measured data, the correlation between the IRI and the average clearance of the threemeter ruler is established. Based on the fact that the performance data of cement concrete pavement in military airport accumulate less, the damage status and flatness data several airport cement concrete pavements with similar service environment to our army fitted and analyzed using the method of space generation time. The correctness of the preventive maintenance timing model has been verified, and the specific parameters of the model have been obtained. It can be found that the fasted decay threshold of the damage index, unique to that exists, by the damage indexIRI relationship. Then the damagedecay model is used to find out the useful life of this value, which is the best preventive effect maintenance time.