The system performance of Spatial Pulse Position Modulation (SPPM) is poor in turbulent channels. In order to solve this problem, the bit complement orthogonal space time Block Coding for Spatial Pulse Position Modulation (BCOSTBC-SPPM) is proposed by combining space-time block codes with spatial modulation technology to improve the bit error rate performance using the space-time coding information redundancy. Based on Maximum Likelihood （ML） detection, the bit error rate expression of the proposed modulation is derived and is verified by Monte Carlo simulation. The simulation results show that compared with SPPM, the error performance of BCOSTBC-SPPM is greatly improved. At the bit error rate of 10-4, (4,2,4)-BCOSTBC-SPPM improves the signal-noise ratio by about 10 dB when comparing with (4,1,4)-SPPM under weak turbulence. Compared with the traditional orthogonal space-time coding scheme, this method has a certain improvement in spectrum efficiency, and realizes a reasonable trade-off between system effectiveness and reliability.