Covalent organic frameworks (COFs) have recently received significant attention as effective photocatalysts which rely on the selected photoactive building units. Benzoselenadiazole is one such unit that enables swift light-induced charge transfer and therefore could be used to construct COFs for photocatalytic conversions. Herein, in the presence of an organobase, 1,3,5-triformylphloroglucinol (Tp) and 4,4′-(benzoselenadiazole-4,7-diyl)dianiline (BSe) are adopted to construct a highly crystalline COF, TpBSe-COF. As designed, TpBSe-COF could implement the blue light photocatalytic conversion of organic sulfides to sulfoxides more adequately than TpDT-COF. Conspicuously, introducing the benzoselenadiazole unit into COFs can broaden the visible light absorption and accelerate electron transfer. Moreover, the synergy between TpBSe-COF and TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) for selective photocatalysis could significantly improve the conversions of organic sulfides to sulfoxides with molecular oxygen. This work suggests the vast potential of benzoselenadiazole COFs in selective photocatalytic conversions.