Some classes of generalization of convexity are given in the case of fractional semi-infinite programming problem, that is, Fε-convex function, Fε-quasi convex function and Fε-pseudo functions. In the framework of the new concept, a Mond-Weir type dual for a class of fractional semi-infinite programming problem is considered. Appropriate duality results are proved. The results obtained not only extend some of the present researches and provide a measurement of sensitivity for given problems to perturbations, but also can be apply to the questions occur in resource allocation, stock cutting problem in paper industry, agricultural planning and portfolio selection etc.