A new method was designed for calibrating a Rogowski coil of fast time response. The method is based on the cable pulser method except that the voltage signal pick-off output was moved to a position with a distance l from the load. If 2l/v is longer than the time duration of the forward voltage pulse u(f)(t), the reflected voltage pulse u(r)(t) could be separated from u(f)(t) and directly measured. Using the formula i(t)=[u(f)(t)-u(r)(t)]/50 to calculate the primary current of the Rogowski coil, the coil could be more accurately calibrated.