In the field of power electronics and instrumentation, SCR is a power electronics device used and the analog gate trigger circuit of SCR is often designed to trigger the SCR. There is nonlinear relationship between the conduction angle of the SCR and the input signal of the analog gate trigger circuit. The nonlinear can introduce the errors into the control system and the nonlinear compensation is difficult to do. The paper takes the double base diode as an example and designs a analog circuit which is used to trigger the SCR and there is the linear relationship between the conduction angle of the SCR and the input signal of the analog circuit. The circuit's practice reveal that it is reliable and practical method of triggering the SCR.