We design and develop a Cassegrain off-axis reflection system collimator with a focal length of 8 m according to production requirements and construct an advanced installation and adjustment method to accurately calibrate it. Through the interpretation of images and interference fringes, the imaging quality of the collimator system is found to be close to the designed value. We solve the problem of the infrared discrimination test target board in production because the longest focal length of the existing collimator focal length is 3 m, and there is no corresponding spatial frequency required by the product.