In this study, a micro-ultraviolet spectrometer with an IV-type optical system is designed, fabricated, and analyzed. The micro-ultraviolet spectrometer is effectively validated for online real-time analysis applications. The main parameters of the prototype include a wavelength range of 200-400 nm, resolution of 0.31 nm, wavelength accuracy of ±0.1 nm, and a signal-to-noise ratio of 507∶1. The experimental results of a 12-h system stability test suggest that the spectral fluctuation is less than 0.47%, confirming the long-term stability of the spectrometer. Finally, the performance of the spectrometer is verified by measuring SO₂ gas at 25 ℃. Based on the theory of differential absorption spectroscopy, a differential absorption cross section calculation of a standard gas is performed. The test results show that the inversion mass concentration of the spectrometer test data has a fluctuation of less than 1%, linearity error of less than 0.6%, and maximum indication error of -0.56 mg/m ³ upon testing an SO₂ mass concentration of 20-100 mg/m ³ for 24 h.