The photolysis rate and its measurement technology were first proposed by German scientists; Metcon developed the photolysis rate measuring instrument in the early 21st century, and then the technology received attention in China, and some universities and companies in China carried out research, and development on the photolysis rate measurement system. However, foreign products are generally larger and more expensive. Core devices such as spectrometers and receivers in domestic products still rely on imports and are vulnerable to foreign technology blockade. Under the guidance of the key project of “Comprehensive Control of Atmospheric, soil, and Groundwater Pollution” in China's “14th Five-Year Plan” National Key Research and Development plan, a spectrograph system for measuring the photolytic rate of atmospheric substances was developed and met the requirements of localization of its core components. The system uses a small spectrometer designed by ourselves as the core component and an optical receiver with uniform response in all directions to measure the photolysis rates of various substances after laboratory optical calibration. The operating band of the system is 285~430 nm, and the time resolution can reach 0.1 s. The measured substances include NO₂, HONO, HCHO, H₂O₂，etc. Compared with the imported measuring instruments, the measurement error of the photolysis rate of each gas substance is less than 5%, and the correlation is more than 0.93. This system has continuously monitored the photolysis rate of gases in the atmosphere on Dongpu Island, Hefei City. The trend of NO₂ photolysis rate and the correlation between NO₂ photolysis rate and concentration were analyzed. It was found that the photolysis reaction was closely related to the energy driving the photochemical reaction, and the photolysis rate value was significantly higher on sunny days than on cloudy and rainy days. At the same time, it is found that there is an empirical formula between the integration curve of NO₂ photolysis rate and concentration; the correlation is greater than 0.9, and the accumulation of NO₂ concentration can be estimated by measuring the NO₂ photolysis rate. The system realizes the localization of core components, the overall structure is simple and portable, convenient for field test and installation, and reduces cost and improves economy. This study provides data support for comprehensive monitoring and control of air pollution and has reference significance for environmental monitoring and pollution prevention in various regions.