For the reliability growth tests with delayed-fix mode, the life in a stage can be assumed to follow the exponential distribution with a constant failure rate. However the reliability between stages has a growth. Usually, growth factor was used for the information transfer between stages. Thus the determination of growth factor becomes very important. The limitation of ML-Ⅱmethod commonly used is analyzed and a modified ML-Ⅱmethod is given. Then Bayesian evaluation method of reliability is deduced. At last, the example shows the feasibility of the modified ML-Ⅱmethod.