This thesis is discussing the protection making use of turbo code to encode and decode，and make use of multilevel way to transmit，because turbo code in white Gaussian Noise channel that have strong correct ability，and utilize the Parallel concatenated convolutional codes system that Berrou put forward to encode，make performance quite close to Shannon limit through perform algorithm to decode repeatedly，and it is the way to adopt Block Code Modulation to transmit the structure multilevel，by this can get code gain of demand and can't increase demand wide of frequency，when the data meet external noise to interfere during the process of transmitting，can make use of such a method to get the result of protecting，we can know result of experiment simulation，it can really raise the exactness that the data are being transmitted and reduce error affect after adopting the turbo code and multilevel way to transmit，therefore improve systematic efficiency.