Vector wavefront aberration theory can quantitatively describe the wavefront aberration of optical systems under the influence of decenter and tilt of sur-face.Based on the vector wave aberration theory,wavefront aberration of misaligned optical systems can be analyzed to guide the alignment of optical sys-tems.The precision alignment of a two-mirror reflective telescope is researched;whose focus and diameter is 562.49mm and 150mm respectively,and theco-axiality is required to be better than 0.008ram.