Abstract: The motion state and parameter estimation of small celestial bodies are important prerequisites for the successful implementation of small object attachment and sampling detection. Key parameters such as rotational angular velocity, inertia ratio and principal axis direction of small celestial bodies need to be obtained. However, due to the lack of markers and communication, and the typically tumbing motion of small celestial bodies, which are typical non-cooperative targets in space, estimating their motion state and parameters becomes a highly challenging task. In this paper, it is proved that the angular velocity, inertia ratio and other parameters of the attitude motion of the non-cooperative target in space are fully observable only by monocular sequence images, and the parameters such as the attitude motion and inertia ratio of the non-cooperative target are estimated by mathematical simulation, and the effectiveness of the method is verified by mathematical simulation.