The invention discloses a method for unified inverse time limit zero sequence overcurrent protection of a distribution network based on negative sequence impedance acceleration, which comprises the following steps: step 1, when a single-phase ground fault occurs on a distribution line and after a segmented switch located on a fault path on a fault line senses a zero-sequence current higher than astartup value, path fault information is uploaded to a transformer substation outlet switch by means of a communication channel; step 2, the transformer substation outlet switch counts the number N ofthe fault switches, and the number N is fed back to the segmented switch through which the fault zero sequence current flows; step 3, the action time of the segmented switch is calculated according to the N value and the zero sequence current value. When the prior art is directed to the single-phase ground fault of the non-effectively grounded power distribution system, the current inverse time limit current protection usually needs to be set to the power supply side from the end of the line step by step; the inverse time limit constant of each stage is limited by the lower level protection;different time constants are adopted to open the time difference at each protection installation, so the setting is very cumbersome and other technical problems.