Abstract: To improve the communication rate of integrated radar and communication (RadCom) signals based on orthogonal frequency division multiplexing (OFDM), data should be modulated by high-order quadrature amplitude modulation (QAM) on each subcarrier, therefore the radar signal performance of QAM-OFDM RadCom signals deserves lucubration. To solve this problem, the influence on match filtering and target detection performance brought by QAM is studied. Moreover, the formula of signal-to-noise ratio (SNR) loss and generalized target detection probability is deduced. Theoretical derivation and simulation results show that QAM with order greater than four leads to the SNR loss in the process of match filtering, but the loss can be alleviated by increasing the time bandwidth product. When the time bandwidth product is greater than 256, the performance of QAM-OFDM RadCom signals are almost the same with the conventional radar signals. Besides, the performance won′t be degraded by enhancing the modulation order. This indicates that QAM-OFDM RadCom signals are suitable for high speed communication in the RadCom system.