With the aim of solving two problems that the performance of the separation coding system in the wireless communication coding filed is limited; the traditional bit-grade grid decoding method can not make full use of the residual redundancy of the information source variable length coding, a novel combined information source channel decoding algorithm based on the symbol-rate super grid graph is proposed. A parallel cascade connection coding model of the information source variable length coding and the channel Turbo coding and the iteration decoding model of the parallel cascade connection coding model are constructed through the combined optimum design of the information source variable length coding and the channel Turbo coding. The state combination is processed on basis of the symbol-rate variable length information source code grid graph and the symbol-rate variable length convolution code grid graph to obtain a symbol-rate super grid graph; based on the super grid graph, the variable length symbol maximum posterior probability decoding algorithm to process combined decoding; the residual redundancy of the information source variable length coding is used to reduce the symbol error rate of the data transmission; the whole performance of the coding system is improved. The combined information source channel decoding algorithm is applicable to the variable length coding transmission system such as the image and video compression in the wireless communication system.