Abstract: In view of problems of high noise and low illumination of coal mine image under complicated circumstance in coal mine, the paper proposed a denoising algorithm for coal mine image based on coupled second-order and fourth-order partial differential equations. The algorithm uses difference curvature edge detection operator to couple the second-order and the fourth-order partial differential equation models effectively, so as to preserve image edge, and uses scale factor to preserve texture detail of the image. The experimental results show that the algorithm can preserve edge and texture detail of the image well, has fast convergence speed, and avoids staircase effect.