Energy saving and high efficient research of electric hydraulic excavator is an important research direction in recent years. How to test characteristics of motor in mobile devices and strong electromagnetic interference environment, especially for motor speed precise measurement, is a difficult problem which must be solved. A high frequency pulse encoder signal transmission method was proposed based on the plastic optical fiber, and the characteristics of the transmission wave shape, the effect of different filter capacitors on the pulse signal at the same frequency and the delay characteristics of pulse signal under different frequency were analyzed. The method was successful used in the electric hydraulic excavator。The test results show that this method has the advantages of long transmission distance, strong antiinterference ability and excellent velocity measurement stability.