To improve the precision of phase difference estimation for sinusoidal signals,a correlation theory-based phase difference estimation method for sinusoidal signals is proposed.Estimated phase estimation is obtained by estimating frequency based on adaptive notch filter,generating reference signals,and multi-layer sliding cross-correlation between reference signals and sampled signals.Theoretical analysis indicates that the proposed method is not affected by non-integral period of sampled signals.To validate the proposed method,computer simulations and field experiments are performed.Simulation results demonstrate that the proposed method has better estimation performance than the discrete Fourier transform method,the data extension-based correlation method and the quadrature delay estimator.The measurement results of Coriolis mass flowmeters verify the effectiveness of the proposed method in practice.