The invention discloses a method of clipping edge peak power in a time slot. The method is: store the data sequence with edge peak value power point into a buffer in order and position the peak power point in the center of the buffer; insert random numbers in the buffer hollow position or output redundant data exceeding the buffer and fill the buffer with input data; double clip the data sequence with the peak value power point in the buffer and the corresponding peak clipping sequence. The invention also discloses a device used to clip the edge peak power in the time slot. The invention can perform peak clipping to the signal edge peak value power in the time slot, with no change to the prior peak clipping sequence length, in order to reduce signal peak-to-average ratio and reduce non linear distortion of the power amplifier caused by the edge peak value power point in the time slot.