Space-time coding technique and Multi-carrier CDMA (MC-CDMA) technique have been research hotspots due to their high frequency spectrum efficiency and high data rata transmission. On the basis of analyzing the two technique principle, by the use of the optimized complex orthogonal wavelet packet and space-time coding technique, we propose a complex orthogonal wavelet packet based MC-CDMA system with space-time coding, and investigate the system bit error rate performance over Rayleigh fading channel. Theoretical analysis and simulation results show that the proposed complex wavelet packet based MC-CDMA (CWP-MC-CDMA) system outperforms conventional MC-CDMA system and it is slightly superior to the conventional MC-CDMA with cyclic prefix (CP). Without any CP, the system has much higher spectrum efficiency. Especially, the application of space-time coding technique significantly improves the system ability to combat channel fading and various interference. Moreover, the space-time coded CWP-MC-CDMA system has comparative superiority to space-time coded MC-CDMA with CP.