Erecting opening in a steel beam web yields to strength and stiffness problems. This paper discusses retrofitting of web opening in steel beams under static load using FRP composites, to bring back the beam strength and stiffness. The study was carried out via a three-dimensional non-linear finite element model. Two different web opening shapes; circular and rectangular; in two different positions; shear zone and mid-span; were concerned in the analysis. Existence of web opening reduced the capacity of the steel I-beam and caused stress concentration around the opening as well, especially at shear zone which lead to vierendeel failure. The adequate strengthening length, strengthening scheme, FRP types, FRP thickness and FRP material properties were studied to come to a conclusion for the most appropriate strengthening technique to bring back the strength of the original steel I-beam. The results revealed that all the strengthened steel I-beams showed a better behavior, a lower stresses concentration around the web opening and presented a higher load capacity. The applicability of the suggested retrofitting limitations on any beam to recover its original capacity was assured by examining the best revealed results on other beams with different dimensions and material properties.