The invention discloses a method and a system for compressing a sparse weight matrix of a convolutional neural network full connection layer, and the method comprises the following steps: 1, obtaininga full connection layer sparse weight matrix A of a convolutional neural network to be optimized, and decomposing the weight matrix A into a position matrix B and a non-zero value array C; wherein the size of the position matrix B is consistent with that of the sparse weight matrix A; in the position matrix B, the numerical value of the corresponding position with the non-zero value in the sparseweight matrix A is 1, and the numerical values of other positions are 0; and step 2, taking the position matrix B obtained in the step 1 as a binary matrix, and carrying out lossless compression meeting a preset image compression standard. According to the method, the compression rate of the sparse weight matrix of the full connection layer can be improved, and more storage space is saved.