Abstract: The limit-state function containing stochastic and interval variables was given. A hybrid probabilistic and interval mixed model for structural reliability was presented. From failure probability integration, it was derived that the failure probability is the mean value of the failure probability considering the randomness of the interval variable. According to the required precision and considering whether the interval variables were correlated, a certain amount of data were pumped in the range of interval variables, and then the mean value of stochastic failure degrees was calculated as the approximate value of structure failure degree. Monte Carlo method was proposed to realize the analogy calculation. A practical example illustrated the application of the proposed theory. The result was compared with that of other reliability models. It was showed that the theory in this paper can overcome the shortcomings of the hybrid model and has reasonableness and feasibility.