Bell layered space-time architecture (BLAST) is a multi-antenna communication structure with high spectrum efficiency, and it has found wide applications in LANs and WLANs. However, its performance is much poorer than those of other space-time coding approaches. In order to improve its performance, an improved BLAST based on RAKE receiving is investigated. The new system introduces orthogonal spreading sequences (OSS) into the transmitter while retains the basic structure of BLAST. The proposed receiver suppresses interferences from other antennas by the orthogonality contained in the received signals, and extracts information from each receiving antenna by using RAKE receiving principle to construct efficient statistic decision. Simulation results show that the improved system performs well over both frequency-flat and frequency-selective fading channels.