Abstract: In the teaching process of the PLC course at higher vocational colleges, traffic lights serve as a classic project. When designing the timing diagram, three debugging methods involving HMI + PLC virtual-real combined debugging are adopted. These methods enrich the teaching approaches and resolve the challenge of being unable to conduct practical training activities when the teaching materials and training equipment are not well-matched. Meanwhile, the vehicle animation on the HMI adds an element of fun to the learning process.