The invention discloses a high voltage line longitudinal zero sequence direction discrimination method and a device. The high voltage line longitudinal zero sequence direction discrimination method comprises steps of determining a first relative angle difference between zero sequence current on one side of the high voltage line and a phase voltage and determining a second relative angle difference between the zero sequence current on other side of the high voltage line and same phase voltage, wherein if the difference value of a first relative angle difference and a second relative angle difference is in a preset angle difference range, the direction of the longitudinal zero sequence direction is a positive direction, otherwise the longitudinal zero sequence direction is the negative direction. When one phase voltage has PT disconnection, the other phase voltage can be utilized to perform determination in order to avoid the locking zero sequence direction protection problem when the three-phase PT is disconnected. In high resistance fault, the invention avoids the problem that the zero sequence voltage is small and the sensitivity is not enough, which causes the incorrect operation of the zero sequence direction member and solves the problem of the false operation of the zero sequence direction protection caused by the non-faulted line affected by the faulted zero sequence mutual inductance which is related to the weak current and strong magnetic.