Abstract: The smoothness constraint method of image restoration in frequency domain and it s practical application in the remote sensing field are emphasized. The theory b ased on smoothness constraint restoration is introduced, then the remote sensing image of CCD camera with the method is processed. The curve fitting and the mat rix construction of remote sensor's system MTF are discussed and it also exp lains how the parameters of the restoration formula are choosed. Results show th at under certain conditions, the whole system MTF can be effectually improved by smoothness constraint restoration, consequently, the remote sensing image b ecomes clear.