A methodology of study of gear dynamics with the aid of the circuit theory and linear graph methods is presented. In terms of analogy of the force, electric tension is used for the composition of equivalent electrical circuit, which immediately gives the equations of motion. The application of the electrical analogy method for the automation of composition of equation of motion and their analysis are considered for the classical example of a one-stage gear transmission with flexible supports and coupling masses. This technique can be extended to analyse the dynamic characteristics of more complex dynamic systems as a planetary transmission with flexible supports.