In a convolutional neural network (CNN), convolution calculation can account for about 90% of the total processing work. This paper presents the design of a convolution hardware accelerator (CHA) which can support efficient matrix multiplication to speed up the convolution calculation. In our experiment, when a RISC-V Rocket processor is used to simulate the operation of a CNN for image classification, it can achieve a performance speedup of 30.82 with the help of the convolution hardware accelerator (CHA).