Based on the single imbalance fault study on the helicopter rotor, three types of conventional blade faults, trim tab imbalance, pitch imbalance and mass imbalance, are simulated on a three-bladed rotor simultaneously. The power spectrum of vibration signals from fuselage is estimated by using the maximum entropy spectrum estimation. Simulation tests show that when the exponent of autoregression model equivalent to the maximum entropy method is 100, vibration signal features are clearly reflected by the power spectrum. Experiments on the helicopter rotor multiple imbalance faults are designed using the orthogonal experimental design method and are conducted in a wind tunnel. The L9(34) orthogonal table is employed by selecting the fuselage vibrations corresponding to the weight of the lateral 1／rev vibration at the wind speed 10m／s. The results of orthogonal analysis show that the interaction among helicopter rotor multiple imbalance faults exists, of which the blade pitch imbalance has the chief effect on the fuselage vibrations.