The invention discloses an improved method for low-voltage ride-through phase-locking of a grid-connected converter. When the voltage drop of a grid is k times higher than a rated value, double rotation coordinate transformation is performed to obtain a positive-sequence Q-axis voltage Uq for per-unit processing. When the voltage drop of the grid is k times lower than the rated value, the input ofa proportional integral part is disconnected, and the output of a phase-locked loop is maintained through the integral part. According to the invention, the problem of phase-locked failure due to unreasonable proportional-integral parameters because the voltage drop causes a decrease in the Q-axis voltage Uq is avoided through the per-unit processing, and the problem of phase-locked failure due to an over-low grid voltage is avoided by maintaining the output of the phase-locked loop through the integral link.