The geometric parameters acquisition of splice detector is the most important thing to validate and evaluate the success of splice, but there is no systematic approach to solve it. For the rotation between the two detectors, the translation of the vertical slit, the slit width and other geometric parameters, the method based on imaging can give very accurate results. On the other hand, the smart-scope can give us the actual mean width of detector splicing, and the results are similar to the above. It proves that the method based on imaging can complete various geometric parameters tests with a very high precision. It just meets the needs of easy and high precision of the aerospace application, and it can provide powerful technical support for the detector slit splicing.