This invention relates to a method to reduce the peak-to-average and orthogonal frequency division multisystem with low peak-to-average, the core of the invention is: before anti-Fourier IFFT transform, the transmitter completely removes or retains part of the initial phase of modulated transmit sequence, and add the transfer function; the receiver removes the transfer function obtained after fast Fourier FFT transform in the frequency domain sequences, carry through the initial phase processing to the frequency domain sequences removed the transfer function, then resume to this transmit sequence. The invention only does N times complex multiplication when adding the transfer function, so it can reduce the implementation complexity of the transmitter and receiver under the premise to effectively reduce peak-to-average. In addition, through the use of this method of keeping part initial phase of transmit sequence by multiply initial phase of transmit sequence with phase factor, the source do not need to send any redundant information like side band information, therefore further lower the implementation complexity of transmitter and receiver.