Abstract: The characteristics of long delay,great error rate and packet loss,asymmetric bandwidth between uplink and downlink and links easily interrupted in deep space communications determine that the technology of encoding and decoding is a difficulty in deep space communications.The basic concept and characteristic of fountain codes are introduced,and the question of full-selected,degree distribution and the decoding algorithm of fountain codes and the performance of decoding algorithm of LDPC are analyzed.On the basis of these analyses,the concatenated codes of LDPC codes as the inner codes and fountain codes as the outer codes are proposed to use in deep space communications.Finally,the result of the cascaded codes having good performance and comparatively simple decoding complexity is obtained by analyzing the performance of the concatenated codes.The concatenated codes can satisfy the reliability requirements of information transmission in deep space communications and the quality of communication and have great potential applications in deep space communications.