Within the strengthening techniques of masonry elements with Fiber Reinforced Plastic (FRP) materials, the use of FRP grid applied with cement based mortar seems to be very promising and interesting, mainly due to the compatibility of the mortar with the masonry supports. A consolidate literature about the effectiveness of such a technique is still lacking regarding experimental results, theoretical studies and code indications. In this paper, the experimental results of shear tests (under a constant vertical load and cyclic horizontal actions) on masonry panels made of adobe blocks and externally strengthened with FRP grids applied with a cement-based mortar are briefly summarized. The attention is mainly focused on the discussion of the outcomes of several numerical analyses developed by a 2D Finite Element (FE) model. The analyses have been carried out in order to examine the effect of some mechanical parameters of the masonry on the non-linear behavior of the tested panels and to assess their values for best fitting the experimental results. Additional parametric analyses have been also carried out in order to verify the effectiveness of the external reinforcement in terms of strength, stiffness and ductility increase compared to the unstrengthened panel as some geometrical and mechanical parameters change.