Abstract: To solve the problem of long time delay and large storage space of the existing turbo decoding, a new state metric re-scaling method and a sliding window algorithm based on sub-blocks are proposed, which is based on the optimization of calculation unit and storage operations, and also we build the register-transmission model for the algorithm.The algorithm combines parallel processing technology and sliding window algorithm organically, effectively reduces the decoding delay and the occupied memory size.The simulation results show that the algorithm has preferable realization without performance degradation.