This article introduces the gradient fidelity term into the functional model of the image denoising to obtain a new denoising functional model and derive the relative nonlinear diffusion denoising model. The new model has been proved that the bounded variation function is integrable, which will get rid of the problem of edge leaking. According to the experimental results, the application of this model is to prevent the "ladder" effect, the result of piecewise smooth can be acquired with more natural visual effects, meanwhile, the method has been proved more stable for the value calculation and has higher computational efficiency.