Power is transmitting by different methods; the spur gear is one of the most important components used in power transmission of mechanical systems. This work presents the effect of face width of gear teeth upon the strength of the spur gear and prepared the analysis of stresses (bending and contact) for the mate teeth. The results gained from Finite Element Analysis (FEA) are compared with AGMA (American Gear Manufacturing Association) equation values, and the 3D model is designed by SolidWorks 2017, saved in IGES format file, and then imported in the ANSYS 16.1 where it can be analyzed. Three models with different values were used in the face width (30, 35, and 40 mm) that is given nearly comfortable of results with a little percentage error different (4.74% for bending and 4.84% for contact). The results are indicated, when the face width increases, stresses are decreases and vice versa. In addition, from the observing of results, we can depend that the used Ansys software to predict the stress values for the improves a design.