Second-order objects has extensive representation in the process control systems. In order to solve the problem of the output response of second-order system under different input conditions, a differential mathematical model of the relationship between the input and the output is established by taking the second-order RLC oscillator circuit as an example. By using the continuous difference method, the recursive relation model of digital input and output in time domain is obtained. The real-time simulation experimental program of the second-order system is compiled based on Kingview software. During the running of the simulation program, any parameters of the system can be given or modified at any time through the simulation interface, and the data and curves of the object response process can be output and displayed in real time. The simulating system has important reference value to adjusting the parameters of controller and the operation teaching of workers in the actual production process.