Abstract: In the signal space diversity(SSD) system, the sphere decoding(SD) algorithm can reduces the complexity of the receiver, but it is high that computation complexity of traditional sphere decoding algorithm at low signal to noise ratio. In order to reduce the computation complexity, the influence of the initial search radius on the sphere decoding process is analyzed, and use optimization ability of wolf pack algorithm to obtain the best initial search radius. It can ensure decoding performance and reduce the computation complexity effectively. The simulation results show that the performance of sphere decoding algorithm based on wolf pack algorithm can be the same as that of traditional sphere decoding algorithm, and can reduce the computation complexity at low signal to noise ratio effectively.