Abstract: This paper proposes a new antenna-packet-activate scheme to address the high complexity problem of signal detection in the large scale multiple-input multiple-output (MIMO) system with generalized spatial modulation (GSM). First, a scheme is proposed to activate the packet-transmit antennas and obtain the selection of the antenna index. Then, the antenna combination symbols are sorted according to the size of quality factor. Finally, we follow the reliability judge rule (RJR) to detect of quantized decision to achieve ideal results. Compared with conventional algorithms, the proposed method avoids to traversally search the signal space, and the performance under the large scale antennas system is better. The calculation and simulation results show that the complexity and bit error rate of the proposed algorithm are quite low, which has high engineering application value in the generalized spatial modulation communication system.