Research on method of small sample maintainability verification test. Firstly take the prior data into identity check by use of rank test in Matlab toolbox; Secondly use the method of information amalgamation based on weighting factor to confirm the mixed prior distribution; Finally will get the scheme of small sample maintainability verification test based on the mixed prior distribution by use of probability likelihood radio method. Examples show that the method can reduce the field test sample size, lower test cost and shorten the test cycle, to improve military economic benefit.