Abstract: In the non-linear conservative system，the spring pendulum has simple structure and

typical motion characteristics. In this paper，the motion equation of the spring pendulum system is

obtained through the theoretical analysis of the Lagrangian equation，and the motion is

decomposed in the radial and tangential directions. The spring pendulum demonstrator and

experimental software are designed by using image processing technology to visu- alize the motion

track and time sequence diagram The trajectory drawn by the software is in good agreement with the

theoretical results.

Key words: spring pendulum, image processing, Lagrange equations