When designing a weapon system, test points should be chosen rationally in consideration of the requirement of BIT: ATE and manual test. At first, it is needed so analyze the design reference and operating requirements, then to choose the test parameters of objects under test at various levels. This method can reduce workload, and avoid setting the test points repeatedly. This paper is focused on how to optimize the test points. A detailed analysis of an example is given. Calculation method of rest weight value (W-FD) is discussed. Test points are chosen according to their W-FD. TP takes priority of selection due to its bigger weighs value. On the basis of the process of selecting test points, system diagnostic program or diagnostic test can be determined, and they also can be used as the foundation of manual test or designing diagnostic software . Finally, the paper puts forward the rule of choosing TP and problem needed to take attention.