Abstract: Based on the water bath method in measuring the metal wire expansion coefficient, a measuring device of the metal wire expansion coefficient for physics experiment, with the high-frequency oscillation circuit as an important component, has been designed. In this device, the metal tube to be measured is connected to the metal plate of the capacitive sensor through an adiabatic cylinder and an insulating cylinder which both are hermetically sealed and free-sliding. Due to thermal expansion of the metal tube, the capacity of the capacitance sensor changes synchronously, which can modulate the frequency of the external high frequency oscillator circuit. Then, the accurate value of the metal wire expansion coefficient can be calculated indirectly by measuring the oscillation frequency and related physical quantity. So, the device can converted the distance variation into oscillation frequency change innovatively. As the device is quite simple, small, it can save space effectively and increase students’ interest in experimental.