Aircraft Battle Damage Repair (ABDR) is the best way for the battle-scarred aircrafts to fly again.The ABDR time assessment is very important for evaluating the battle damage degree of the aircraft, and is also a main precondition for making urgent repair.Considering that the ABDR time assessment is influenced by many factors, the Principal Components Analysis (PCA) method is used for dimension reduction, which transformed the large number of influence factors into uncorrelated new variables, known as principal components, which are linear combinations of the original variables.The achieved principal components are explained from a new insight.A multiple linear regression model is built for assessing ABDR time.The regressive parameters of the model are optimized through Genetic Algorithm (GA).The following results are obtained by using PCA method:1) The 12 ABDR time assessment influence factors are reduced to 6 new principal components, which decreases the input numbers and complexity of the regression model effectively;and 2) The error of ABDR time evaluated by the optimized regression model is smaller, with an average relative error of 12.82%.