Abstract: Fast and accurate extraction of the sequence components for three-phase voltage is a basic condition for improving the control capability of power electronics grid-connected systems. Focusing on obtaining the voltage sequence component under three-phase unbalanced grid conditions, this paper uses a variable samplings filter（VSF） algorithm to rapidly separate the positive and negative sequence voltage component by delaying two sampling periods of voltage component in the dq frame. By analyzing the noise amplification rule of the proposed algorithm, the adjustment performance of VSF algorithm is used to limit the noise level in the output signal. Finally, the superiority of the above algorithm is verified by MATLAB simulation and DSP experiment results.