To address the deficiencies of existing metal detectors in accuracy and sensitivity, this paper presents a portable metal detector based on the STM32 microcontroller. The system adopts an RC oscillation circuit as the signal transmitter and an LM324-based circuit for signal reception and processing. A combined amplitude and phase detection method is proposed to accurately identify metal types and locations. An adaptive filtering algorithm is applied to suppress environmental noise and improve detection precision. The optimized coil with high-permeability material and a multi-layer winding structure enhances sensitivity and anti-interference performance. A low-power power management module extends working time, making the device suitable for field and mobile applications. The main innovations include intelligent metal identification, optimized coil design and signal processing, as well as user-friendly human-computer interaction. Compared with conventional detectors, the proposed system exhibits significant advantages in precision, sensitivity and intelligence, providing an efficient and reliable solution for related applications.