The invention discloses a determination method of a lightning arrester early warning value and a device. The method comprises steps of constructing a current distribution model of a lightening arrester in a target region according to monitored current data of the lightening arrester in the target region, wherein the current data comprises total-current data and/or resistive current data; acquiring the defect rate and/or the fault rate of the lightening arrester in the target region; and according to the current distribution model and the defect rate and/or the fault rate, determining the current early warning value of the lightening arrester in the target region. According to the invention, the technical problem of inaccurate current early warning value of the lightening arrestor in the prior art is solved.