Abstract: In response to the reliability of the endpoint motion accuracy of space manipulators under the impact of high and low temperature alterations, the factors affecting their motion reliability were analyzed. Taking the endpoint position accuracy of the manipulator as an evaluation index, a kinematic model with variable coupling tolerance was established, which considered uncertain factors including arm deformation errors, joint manufacturing errors and assembly errors, etc. And then, the reliability of the endpoint trajectory and the continuous trajectory of the manipulator were analyzed. Finally, the endpoint attitude reliability model of the manipulator based on space alternating high and low temperatures was established. This model was applied to study the reliabilities of position accuracy and attitude accuracy of four endpoints in the motion trajectory of a manipulator under typical working conditions, and the probability of pose failure was obtained. The proposed study may provide a theoretical support for the reliable operation of space manipulators in orbit.