Gear is a mechanical rotating toothed part which meshes with other similar toothed parts to transmit torque and power. Gear tends to play a very vital role in all industries. This article reviews the methodology used to investigate bending strength of asymmetric spur gear; Finite Element Method (FEM), Numerical Calculation and Investigational Techniques were usually carried out in order to understand the bending strength of spur gear. Works and experiment from the literature were studied, and their findings were extracted to understand the methods used. Next stage is to simulate the gear using Finite Element Method (FEM) in order to get the analysis of gear strength. The most important stage is to put the gears to physical experiment or testing facilities to determine and validate all data from the numerical calculation and FEM method. Therefore, this review article highlights importance of asymmetric gear in chronological order so that reader may obtain an overview of contribution of various researchers in development of gears having least bending stress. Keywords: Symmetric gear, Asymmetric gear, Bending stress and FEM.