Aiming at the research of pollutant diffusion prediction in the field of water environment, it is difficult to achieve the real-time measurement of concentration field in large area of water. A multi-channel fluorescence concentration measurement system was designed, and the system hierarchy architecture of sensor, acquisition device and upper computer was proposed. A photoelectric concentration measurement sensor based on the principle of laser induced fluorescence (LIF) was developed, the LED excitation light source modulated by the frequency was adopted by transmitting part, and the filter set and photocell were adopted by receiving part. The isolation reflective cover with a bamboo hat structure style and the signal processing circuit were innovatively designed, which could extract weak fluorescent electrical signals from water bodies and avoid the influence of natural light sources and interfering light sources on electrical signals. After laboratory tests, the measurement range of fluorescence substance concentration in the system is 0.001 mg/L to 0.040 mg/L, the resolution is 0.001 mg/L, and the measurement error is not exceeding 5%, which verifies the system running stably and reliably for a long time. The system has been applied in the project referring to the research on environmental pollution prediction of nuclear power plants, which lays a foundation for the correctness and reliability of the experimental results in physical model test of environmental pollution in nuclear power plant, and has good promotion and application values.