Based upon the horizontal displacements data in-situ in the top of concrete gravity dam, the parameter identification problem is done with the regularizing least squares method for the elastic modulus of the concrete gravite dam. The iterative format and selecting algorithm of the regularizing parameters are set up. It is also put forward to identify material physical properties according to the priori information. The practical use of the parameter identification algorithm proposed shows that this algorithm has fast convergence speed and good stability.