Through discussion of the characteristics of complex diffusion, a novel adaptive complex diffusion algorithm based on diffusion parameter and iterative step is proposed to overcome the disadvantages that the diffusion parameter k and iterative step Δt are constant. This new algorithm used the gradient information of image’s real part to control the diffusion strength to realize different diffusion velocity in different gradient region, and increased the iterative step with increasing iteration number, so this adaptive complex diffusion can achieve better denoising effect in less diffusion time. Numerical experiments results show that this algorithm can remove the noise while preserving more image details and gain higher peak signal noise ratio in a shorter time.