Abstract: According to the variation rule of failure intensity of repairable systems,and with a view of the influence of inter-failure time,a generalized reliability growth(GRG) model was developed,and the property was analyzed from different parameter values.Additionally,the trend test was also presented.Secondly,maximum likelihood estimation of the parameters was given under time censored and failure censored test.The Simpson rule was used to change the integral formula into the function of sum.The goodness-of-fit test and reliability growth assessment method were presented.Finally,a group of test data of some turbofan engines were analyzed.The result shows that the data is good fitted by the GRG model,and the assessment of the reliability growth is suitable to the engineering applications.