Abstract: According to noise characteristics of aerial image, this paper proposes a kind of wavelet transformation denosing method based on medium filtering for aerial image. The medium filter is applied to reduce image random noise, and wavelet transformation is made on filtered image. Compared to given threshold, the wavelet coefficients that could be judged as signal or noise obviously are processed, other coefficients are processed before running down in multi scale of wavelet. Experiments prove that this method improves image signal to noise ratio objectivley, and makes denoised image more clearly and suitable for human visual observation, which is good for analysis and judgement of aerial images.