Abstract: Based on the enumerate significant failure modes on general reliability of structure static strength, using the entropy concept, a relationship between a random-fuzzy parameter and an equivalent random parameter is presented. With the relationship, it can be made good result on the failure models of the random-fuzzy structures, and an example is given to show the availability and advance of the new method. Finally, after discussed the steps of the optimality criterion, it is pointed out that if combined with the parallel computation, the algorithm will be more efficiently.