Abstract: This paper discusses the numerical algorithm for a class of two-level programming problems with the lower-level programming problem responding its optimal value to the upper-level programming, in which the objective functions and constrained functions are Lipschitz continuous. By way of constructing the interval extensions of the two-level objective functions and introducing the test rules of region deletion, an interval algorithm for solving two-level programming problems is established and an experiment upon the numerical examples is performed. Both theoretical proof and numerical experiments show that the algorithm is reliable and effective.