Because of the characteristics of the periodic oscillatory motion of the water particles under wave action,the direct observation is difficult.However,the direct observation of the moving water particles under wave action is helpful not only to the further development of the wave theory,but also helps to understand the characteristics of the wave motion.So a new water particles tracing apparatus with a very low cost is presented.This environmentally-friendly and safe apparatus can be applied in observing the orbits of water particles directly,which is simple in structure and easy in operation,and without disrupting other flume experiments.Combined with a series of flume experiments,the working principle and operation method of the apparatus are discussed in detail.The experimental results also show that the apparatus and method are applicable in tracing any water particle in the flume under different wave elements,and the experimental data are in accordance with the wave theory,which proves the practicability and reliability of the apparatus.