In this paper, we analyze a M-ary quadrature amplitude modulation (M-QAM) scheme over twowave with diffuse power (TWDP) fading environment for multiple receive antennas based system. We consider a Selective decode-and-forward (DF) relayed system with multiple receive antennas at the relay and the destination node. Utilizing the moment generating function of TWDP fading distribution, we derive the closed form expression for the exact average symbol error rate (ASER) for MQAM scheme. Moreover, in order to get the better insight of the system, we also perform the asymptotic analysis for the considered system. Simulation results are presented for different scenarios and it is observed that analytical results show excellent agreement with the simulation results.