The principle is to convert resistance，capacitance and inductance into frequency through the corresponding relationship with frequency，which is processed and calculated by Field Programmable Gate Array，and finally output the value on the display screen． The waveform of resistance and capacitance is generated by the multi harmonic oscillation circuit composed of NE555 timer，and the waveform of inductance is generated by the three-point oscillation circuit of capacitance．The frequency is captured by the Digilent Basys 3 development board，processed by the equal precision measurement method，and the results are obtained through calculation，thus realizing the measurement and display of each unknown component．