Pyridinium1,4-zwitterionicthiolates are usually used to develop ionic annulation reactions. However, radical reactions were rare. We developed a photoredox catalyzed [3 + 2]-annulation reaction of pyridinium1,4-zwitterionicthiolates with alkenes, disclosed the new reactivity of pyridinium1,4-zwitterionicthiolate, and provided a new synthetic method for dihydrothiophene.