The excessive accumulation of phosphate and heavy metal lead ions in water bodies is a critical factor leading to environmental eutrophication and ecotoxicity. To address the issues of time consumption and high costs associated with conventional water quality testing, this research aims to develop a highly efficient, low-cost, and high-precision on-site spectrophotometric analysis system. This work achieves a deep cross-domain integration of chemistry, optics, electronics, mechanics, and Artificial Intelligence (AI), encapsulated as "" Optics-Electronic-Mechanical-Intelligence."" The core of the system is a self-developed UV spectrophotometric detector, which combines a UV LED array with a high-precision sensing chip. This detector is controlled by a microcomputer (Raspberry Pi) driving a precision slide rail, forming a modular and portable spectral data acquisition platform. For Qualitative Analysis: The system swiftly and reliably identifies specific pollutants in the aqueous solution. This capability can also be applied to the real-time classified recovery of chemical laboratory waste liquids, contributing to environmental protection. For Quantitative Analysis: Based on the qualitative identification, the system retrieves the corresponding element's quantitative fitting curve to accurately calculate the concentration of the substance in the aqueous solution. The research results confirm that this self-developed system effectively enhances the speed and accuracy of water quality analysis, providing a practical and robust technical foundation for the future intelligent and high-density monitoring of environmental water quality.