Abstract: To address the demands for low power consumption, high performance, and long-term autonomous operation in underwater acoustic signal acquisition systems, an 8-element hydrophone array data acquisition, storage, and real-time monitoring system is proposed in this paper. Built around a TI OMAP-L138 heterogeneous dual-core processor, the system achieves real-time signal processing while maintaining low power consumption. For storage, a SATA solid-state drive is adopted, combined with the AHCI and DMA mechanisms and an optimized write cache strategy, enabling continuous acquisition of 8 channels at 100 kHz for over 13 days of data recording. The analog front end incorporates a programmable gain circuit ranging from 0 to 60 dB, accommodating the wide dynamic range of underwater acoustic signals. The host computer software is developed using PyQt6 framework and adopts a multi-threaded and timer-based architecture. It achieves obstruction-free real-time waveform display for 8 channels through independent threads and a circular buffer, and integrates real-time waveform graphs, spectrograms, statistical analysis, and offline playback functions. Lake trial experiments have verified the engineering effectiveness of the proposed system in data acquisition, storage, and target direction-of-arrival estimation. The system balances multiple requirements including low power consumption, high performance, long-term autonomous operation, and real-time human-computer interaction. The implemented functions of data acquisition and direction-of-arrival estimation can effectively support underwater target detection and marine environment monitoring tasks, demonstrating its potential for broader application.