To address the inefficiencies and significant inaccuracies of conventional coal slurry water concentration detection methods in coal preparation plants, a detection device utilizing a photoelectric approach has been developed. This device employs photoelectric sensors, temperature sensors, and a microcontroller unit (MCU) to measure the voltage of the slurry water, subsequently calculating the corresponding concentration value through a mathematical model that correlates the concentration of coal slurry water with the sensor output voltage. The research findings indicate that the concentration detection system can identify concentration signals in real time, incorporating data processing, software calibration, and temperature adjustment functionalities. The detecting system can precisely measure the concentration of coal slurry water within the range of 0-20 g/L. The concentration detection gadget operates and is cost-effective to produce, addressing the limits of conventional detection methods while enhancing the efficiency and automation of coal selection.