In this research, a computer-aided drawing system of spur gear was developed. An auto LISP programming language embedded within the AutoCAD design package was used to develop a new program to create a 3D model of a spur gear in two main stages. In the first stage, the developed program of spur gear allows automatic 2D spur gear drawing generation using the technique that depends on the half tooth thickness at the pitch diameter. In the second stage, inner profiles of a 2D spur gear views are used to create a 3D model of a spur gear. The developed program helpful for the user in drawing the spur gear modelling, due to less work and time to be spent when compared with the conventional approach, and it also improves a high degree of accuracy of spur gear modelling. The spur gear resulting from the prepared gear drawing system can also work with other popular CAD software.