The invention discloses a self-adaptive amplitude limiting method for reducing peak-to-average power ratio of an OFDM (orthogonal frequency division multiplexing) system. By researching the relationship of time domain signal variation and frequency domain signal variation in the amplitude limiting algorithm, and on the basis of probability distribution of time domain signal amplitude, the invention proposes a method of setting the amplitude limiting rate adopted in the amplitude limiting process according to the energy of statistical difference value signals exceeding a set threshold; and when the method is applied to the constraint amplitude limiting algorithm, the self-adaptive amplitude limiting of an OFDM symbol is realized, and the peak-to-average power ratio (PAPR) of the OFDM system can be effectively lowered. As indicated in theoretical analysis and simulation, and compared with the constraint amplitude limiting algorithm with fixed amplitude limiting rate, the self-adaptive amplitude limiting method has better PAPR performance.