The parameter identification is necessary for precise control orbit and attitude of Space Robot. This paper presents a method for parameter identification of inertia properties of space robot which is based on the momentum conservation. As the initial momentum of the Space Robot is hardly known, we have to discuss detailed in two options. The first option, the initial momentum is known and assumes it is zero, then we can solve all the unknown parameters in the momentum equations; the second it’s unknown, it has to be solved in two steps. The first step is to identify the mass and mass center of the spacecraft; and the second step is to identify the inertia tensor of the spacecraft. In the end, we build the model for simulation; the result shows that the method has the high precise and the error can be ignored.