Inter modulation (SM), as a novel multi antenna transmission scheme, creates a mapping relationship between input bits and transmit antenna ordinal numbers, which is used to carry certain transmission information. However, the scheme maps the sending bits to a uniform distribution signal constellation through a single layer modulation mode, which greatly limits the performance of the system. Hierarchical map coding (SCM) technology is applied to constellation point mapping, which satisfies different quality of service (QoS) requirements of different data services on the same transmission slot, and effectively improves system performance. Based on the principle of SCM, a low complexity detection algorithm is proposed. The simulation results show that the detection performance of the new algorithm is approximate to the maximum likelihood (ML), and the complexity of the receiver increases linearly with the modulation order.