Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works. This paper is a part of a general research designed to the application of topology as a new approach for the modeling of mechatronic systems. Particularly, the modeling of a one stage spur gear transmission using a topological approach is tackled. This approach is based on the concepts of topological collections and transformations and implemented using the MGS(modeling of general systems) language. The topological collections are used to specify the interconnection laws of the one stage spur gear transmission and the transformations are used to specify the local behavior laws of its different components. In order to validate this approach, simulation results are presented and compared with those obtained with MODELICA language using Dymola solver. Since good results are achieved, this approach might be used as a basis of unification for the modeling of mechatronic systems.