Aiming at large amount of samples about maintainability test and evaluation method and it can’t reflect maintainability about the weapon system effectively, put forwards maintainability test method and evaluation method based on sequential gridding theories. Discuss the test method, evaluation method and calculation samples method according to sequential gridding theories in details. Use certain type equipments as an example to verify the method. The result shows, applying the method can reduce test sample quantity, overcomes the defect that we can’t calculate sample quantity before Wald’s sequential probability sampling test, and the biggest sample quantity is the smallest.