Abstract: Spacebased light gas gun (SLGG) provides a more effective way for space attack and defense and space debris removal due to its stable performance and easy miniaturization. The primary precondition of the SLGG to accomplish the task is to strike the space target accurately. To evaluate the firing accuracy comprehensively and accurately, firstly, the shooting error distribution model is established. Three firing accuracy evaluation factors, including shooting accuracy, dispersion and hit probability are formulated. Then, a general framework, including simulation fire test, data preprocessing, fire accuracy evaluation, is proposed to evaluate SLGG firing accuracy. Finally, firing accuracy evaluation of the target with circular orbit at the height of 10354 km is performed via the designed framework. The results reveal that the firing accuracy is about 48 meters and CEP is about 87 meters under current defined scenarios. The errors are mainly caused by the orbit determination of noncooperative target. Moreover, the influence of errors on firing accuracy is amplified due to the long range. The hit probability is about one in a thousand, and increases with the increase of target size.