Sun sensor is one of the key attitude sensors widely used in spacecraft attitude determination. Its accuracy is one of the major technical specifications. In this paper, we propose two methods for accuracy test and evaluation, which have been proved to be efficient and convenient. With these two methods, it is possible to isolate and then, eliminate the rotational error from the rotation table that holds the sun sensor so that the performance of the sun sensor can be evaluated. The proposed two methods can be also applied to test the performance for other angle measuring devices.