Abstract: The spatial modulation (SM), which overcomes several drawbacks of the MIMO system and obtains a higher spectral efficiency compared with SIMO system, has received much attention recently. And the STBC-SM was proposed by combining the STBC with SM to improve the diversity gain of SM. Furthermore, some researchers proposed the star-QAM modulation for SM, which has a better BER performance compared with PSK and QAM modulation. However, the STBC-SM with star-QAM modulation does not have a better BER performance as expected. Consequently, in this paper, a simplified star-QAM modulation is proposed, which applies each ring of constellation point of star-QAM in the different STBC-SM codebook to increase the minimum coding gain distance (CGD). The standard to choose the amplitude of each ring is also presented in this paper. Finally, the simulation results show the performance advantages of the STBC-SM scheme with simplified star-QAM.