The Eccentric-pupil two-mirror collimator is analyzed and its disadvantages are pointed out. The field view of eccentric-pupil two-mirror system is usually small. In order to enlarge field view and to improve image quality, a method of decentering and tilting the secondary mirror is introduced, the primary aberration of the system with decentered and tilted component is simply analyzed using the vector aberration theory. Two designs are given and compared, showing that the method presented could get a good design by enlarging system field and by improving image quality.