The invention provides a light generalized spatial modulation method based on an OB-MMSE detection algorithm. An OGSM scheme is provided by simultaneously activating a plurality of lasers at a transmitting end and combining pulse position modulation. On the basis, an OB-MMSE signal detection algorithm is introduced into a receiving end, and the weight of an OGSM modulation signal is corrected according to the characteristics of the OGSM modulation signal, and therefore, an OB-MMSE signal detection algorithm suitable for optical generalized spatial modulation is provided A selection method of athreshold value in a logarithmic normal turbulence channel is derived. Compared with the traditional light space modulation, the spectrum efficiency of the system is effectively improved, and the limitation that the OSM laser must be an integer power of 2 is overcome. In addition, compared with an ML algorithm, the algorithm provided by the invention effectively reduces the complexity of the ML algorithm under the condition of sacrificing relatively small error code performance.