The invention discloses a device and method for preventing 220kV main transformer gap protection malfunction and solves a problem of cut off of high voltage side power supply of a main transformer because of main transformer gap protection malfunction when main transformer gap protection motion time delay is smaller than the reclosing time set during single-phase grounding short circuit of a lineof a 220kV transformer station. If a gap of a neutral point of the main transformer for gap grounding is broken down by discharging, a neutral point zero sequence current value (3 I0) is greater thana gap overcurrent protection motion value (I0P), and the automatic reclosing signal of the line of the 220kV transformer station during generation of single-phase grounding is received by a gap protection device (5), if automatic reclosing succeeds, gap protection takes no motion; if automatic reclosing fails, gap protection takes no motion. The method is advantaged in that safe and stable operation of the power grid is guaranteed, and power supply reliability is improved.