The method currently used to carry out testability verification under the small sample, varying population condition inevitably has a large number of samples, long verification time, and poor confidence interval. Thus, a new Bayesian verification method is proposed based on the equipment testability growth model. The parameters are calculated from its dynamic growth mathematical model using the existing data. According to the prediction value based on the above method, it can determine the prior distribution and calculate the distribution parameter value using the maximum entropy method. The posterior distribution is obtained from field test data using the Bayesian theory so that the evaluation and demonstration of the testability index can be realized. Practical examples indicate that this method can verify the system with fewer samples at higher confidence, which helps reduce risks for both the consumer and producer.