Abstract: The essential sensing mechanism was investigated for the resonant Coriolis direct massflow meter in detail.The mathematical model of the resonant direct massflow meter was established,based on a typical U-type tube resonant sensing structure.The output signal calculating model was provided for the above massflow meter based on measuring the amplitude ratio.A signal processing circuit prototype was designed and developed by making use of MCS-51 type micro-processor,based on the above output signal calculating model.The testing results show that measuring error is less than 0.1％F.S.for the above developed processing circuit prototype.The theoretical and experimental results obtained here are of practical significance for developing the Coriolis resonant direct massflow meter.