The problem of Total Variation (TV)-based image denoising was considered. Since the traditional serial computation speed based on Central Processing Unit (CPU) was low, a parallel computation based on Graphics Processing Unit (GPU) was proposed. The dual model of the total variation-based image denoising was derived and the relationship between the primal variable and the dual variable was considered. The projected gradient method was applied to solve the dual model. Numerical results obtained by CPU and GPU show that the algorithm implemented by GPU is more efficient than that by CPU, and with the increasing of image size, the advantage of GPU parallel computing is more outstanding.