Aiming at the detection of SO₂ concentration in SF₆ decomposition products in electrical equipment, the design of ultraviolet absorption spectrum analysis module and data processing method were studied. Low power consumption pulsed xenon lamp light source was used to shorten preheating time. A long optical path gas absorption cell with multiple reflections was designed to effectively shorten the response time. The gas consumption was reduced, and the light source and micro spectrometer were directly coupled with the gas chamber, so that the stability was better. The SO₂ concentration was inversed in the 280 nm~320 nm spectral band. The partial least squares regression multiple correction method was used to establish a regression model for the differential absorbance of SO₂ spectral band and the SO₂ concentration, and the errors of the model was less than 0.5 μL/L. The principle prototype was designed, and the feasibility of the design scheme was verified by experiments.