A graphical analysis is developed for the solution of transient response in nonlinear systems. The nonlinear system is first represented by its equivalent circuits with linear and nonlinear R, L, C circiut elements. By applying Kirchhoff's rules of circuit analysis with properly chosen variables, a set of nonlinear differential equations of the desired form is obtained. To solve the equations, integrations are performed on the phase plane with the graphical method proposed in the paper. This method of analysis possesses the following advantages: (1) The nonlinear functions can be obtained directly from exprimentally determined curves. Analytical expressions are not re quired. (2) The calculation is relatively easy and only simple tools are used. (3) Satisfactory accuracy is obtainable. This method of analysis is applied, in particular, to calculate the transient response of basic circuits of tunnel-diodes. Results are in good agreement with the experiments and with those obtained by electronic computer.