A resonant frequency measurement system for a magnetoelastic (ME) sensor based on the impedance response was established and the measuring mechanism, equivalent circuit model and the measuring circuit of the ME sensor were researched. First, the measurement mechanism of resonance frequency was introduced based on the impedance change of the ME sensor. The equivalent model circuit of the ME sensor was established according to the affect of the ME sensor on a coil impedance. Then an impedance measurement circuit based on system-on-chip was designed. Finally, the experiments were performed to verify the feasibility and reliability of the resonant frequency measurement system for the ME sensor. Experimental results indicate that the frequency resolution and the accuracy of the system are less than 0.1 Hz, and 0.5% respectively. Moreover, the deviation between the resonant frequency measurement system and the traditional network analyzer platform is 60 Hz for a same Metglas 2826MB material;the resonance frequency radio of two Metglas 2826MB materials with different lengths is 0.74, similar with the theoretical value of 0.8. The resonant frequency measurement system works well in different media, which means that the system can replace an expensive and large network analyzer and is characterized by higher integration, stronger anti-interference, lower costs and portable measurement.