Engineering design is an iterative process that requires to be followed with all feasible design solutions in order to arrive at desired objective. Proper design of gear train has a significant place in power transmission applications. Traditional methods used in its design do not have ability in automating the process. Thus, an attempt to automate preliminary design of gear train has been accomplished in the paper. In this paper, the volume and load carrying capacity are optimized. Two different methodologies (i) Genetic algorithm (GA), (ii) Fminsearch Solver optimization technique are used to solve the problem. In the first two methods, volume is minimized in the first step and then the load carrying capacities of both shafts are calculated. In this study, the Genetic Algorithm is introduced for the optimum design of gear trains to solve such problems and we propose a genetic algorithm based gear design system. This system is applied for the geometrical volume (size) minimization problem of the two-stage gear train and the gear train to show that genetic algorithm is better than the conventional algorithms for solving the problems. Genetic algorithm is used for optimization by using a Matlab programs are used to solve the problem. For the optimization purpose, face width, module, and number of teeth are taken as design variables. Constraints are imposed on bending strength, surface fatigue strength and interference. The results are validated with the experimental results published in the literature and standard parameters of gear train. © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved.