In order to improve the spectral efficiency of the index modulation scheme in Multiple Input Multiple Output（MIMO） systems

this paper combines Spatial Modulation（SM） with Code Index Modulation（CIM） and uses the idea of parallel transmission to convey the transmission information bits by two modulation symbols

two antenna indexes

and two Pseudo Noise（PN） code indexes in each time slot. In addition

the proposed scheme also uses the antenna selection technique and the rotational symmetry characteristics of the quadrature amplitude modulation symbols to improve the Bit Error Rate（BER） performance of the system and reduce the detection complexity of the receiver

respectively. The simulation results show that the BER performance of the proposed scheme is obviously better than other index modulation schemes

and the low complexity Maximum Likelihood（ML） detection algorithm proposed in this paper has the same BER performance compared with the optimal ML detection algorithm.