The distributed capacitance current of UHV transmission line has a negative impact on differential current protection. Aiming at this problem, a novel accurate compensation method of capacitance current is proposed in this paper. All the factors that affect the capacitance current are taken into account by the variation of the capacitance value. The capacitance value can be calculated on line, based on which the capacitance current can be compensated accurately. Simulation results demonstrate that the proposed method is superior to the fixed compensation method.