Abstract: In view of the problem that the development and design of sonar systems require a large amount of experimental data for verification, but the field-measured data is insufficient, which hinders the full validation of the signal processing capabilities of sonar systems, and to further enhance the accuracy of passive array signal modeling in the sonar system test platform, this paper proposes a Farrow structure variable fractional delay filter design method based on cubic spline interpolation on the basis of the existing sonar system test platform. This method is used to generate high-precision passive array received signals. Compared with the frequency-domain delay method, the continuous spectrum and line spectrum components of the passive array received signals generated by this method have higher accuracy. Meanwhile, the processing results of the signals generated by this method are consistent with those of the measured signals after processing, verifying the effectiveness of this method. The method proposed in this paper provides algorithmic support for the optimal design of the sonar system test platform.