The FDR(flight data recorder) records some parameters of the aeroengine.Because of the jamming,there are some abnormal data in these parameters.The data must be preconditioned so that it can be used to forecast the performance trend of the aeroengine.As a system,there must be some functional relation between the input and output of the aeroengin.This paper researches the preconditioning of the flight data with the RBF neural network and relation of the parameters.Normal data is worked out in this way.So this method is available.