The invention discloses an orange red light thermal activated delay fluorescent material which is 3,6,11-tri(9,9-dimethyl acridine-10(9H)-yl)-dibenzo[a,c] phenazine (3DMAC-BP). The fluorescent material has a rigid large-plane twisted structure and a remarkable internal charge transfer (ICT) effect, has an organic red thermal activated delay fluorescence property (TADF), a high fluorescence quantumyield (PLQY) and excellent thermal stability, and is simple in synthesis preparation steps, and raw materials are easy to obtain, synthesis and purification processes are simple, the yield is high and large-scale synthesis and preparation can be achieved. The organic electroluminescence device based on the material is capable of emitting orange red fluorescence (lambda=606nm), the external quantum efficiency EQE of the device is as high as 22%, and the device has the advantages of being low in driving voltage, good in light emission stability, and the like, and has good application prospectsin fields such as lighting, panel display, sensation, night vision, bioimaging and the like.