The invention discloses a method of determining generator grid connection synchronous closing pulse transmission time, which comprises steps: S100, grid voltage and generator-end voltage in each cycleare acquired; S200, the effective value of the difference between the grid voltage and the generator-end voltage in each cycle is calculated; S300, the effective values of the voltage differences inmultiple cycles are stored to form a voltage difference effective value sequence, and a time sequence with the values to be consistent with the effective value sequence is stored; S400, according to the voltage difference effective value sequence and the time sequence, the correlation coefficient between the voltage difference effective value sequence and the time sequence is calculated, and a linear fitting expression for the voltage difference effective value sequence and the time sequence is calculated at the same time; and S500, according to the correlation coefficient and the linear fitting expression, whether to transmit closing pulses is judged.