An immersive theater system includes a theater device having a projection room and a displaying screen unit, a multimedia audiovisual assemblage disposed in the projection room, and a central control device connected to the multimedia audiovisual assemblage. The multimedia audiovisual assemblage includes lighting units, speakers and projectors. The projectors are installed at different angles to face different display screens of the displaying screen unit. The central control device includes an audiovisual source coupled to the projectors and the speakers, and the audiovisual source is firstly divided and then displayed on the display screens to create an immersive environment whereby audience members in the projection room feel them to be immersed in lifelike surroundings caused by activating the multimedia audiovisual assemblage under the control of the central control device. The immersive theater system can be disposed in a mobile carrier to increase the mobility and the frequency of use.