Abstract: In the integrated radar and communication(RadCom) system which using adaptive modulation technology and orthogonal frequency division multiplexing (OFDM) signals, the RadCom signal usually has a non-rectangular and varying power spectrum, which leads to the deterioration of the traditional side lobe suppression methods, such as the reduction of the peak to side lobe ratio and the increase of SNR loss. To solve this problem, a new range side lobe suppression method for OFDM RadCom signals was proposed. In this method, an adaptive amplitude weighting function is designed according to the power spectrum of emission signals, and the side lobe suppression problem is transformed into an optimization problem. The simulation results show that the range side lobe of OFDM RadCom signal is effectively suppressed under the condition of the spectrum variation or even discontinuous of transmitted signal, and the signal-to-noise ratio loss of this method is much smaller than that of conventional methods.