The invention relates to a low-precision large-scale antenna system based on probabilistic shaping and a coding modulation method thereof. In the low-precision large-scale antenna system, a sending end performs probabilistic shaping coding, channel coding and constellation mapping on information bits, and a receiving end performs low-precision quantization processing, probabilistic shaping detection, channel decoding and reverse probabilistic shaping on received signals, so that the information bits are detected. The coding modulation design method comprises the following steps: analyzing theinfluence of low-precision quantization on transmission constellation diagram energy distribution of the low-precision large-scale antenna system; based on an analysis result and the channel type of the receiving end, optimizing the sending probability distribution of the sending end, and obtaining an optimal transmission sending probability; and realizing coding modulation design based on the optimal transmission sending probability. Compared with the prior art, the low-precision large-scale antenna system based on the probabilistic shaping and the coding modulation method thereof provided bythe invention have the advantages of reducing the capacity loss caused by the quantification and the like.