Magnetoelastic (ME) sensors, characterized by wireless, passive, low cost and high sensitivity, have widespread applications in various fields. However, its defects of large volume, high power consumption, poor portability and inconveniency for use limit the application prospects of the ME sensors. To solve this problem, the present paper shows a portable, low-power, resonance-type ME sensor detecting system based on STM32. The experimental results indicated that this detecting system allowed the ME sensor to complete the measurement of resonant frequency in different medium and different concentration, with a frequency resolution of less than 1 Hz, and the resonant frequency ratio of ME sensors in different sizes 0.933 8, closing the theoretical value of 0.942 3. Moreover, compared with the traditional impedance analyzer combined detecting system and the existing integrated detecting system, the present system has a power consumption of 0.68 W in operation and of only 2.20 mW in the dormancy mode. Therefore, the system can not only replace the original impedance analyzer combined detecting system, but also significantly improve the power control of the existing integrated detecting system, exhibiting the advantages of higher integration, portable measurement, and fine suitability for long-term monitoring.