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