The invention discloses a microbial agent and application thereof to enhanced treatment of coking wastewater and further discloses a method and corresponding device for treating coking wastewater by using a microbial agent. The raw coking wastewater enters an oil separation tank, a regulation tank, an hydrolysis and acidification tank, an aerobic reinforcement tank, a primary sedimentation tank, an anoxic denitrification tank, an aerobic nitrification tank and a secondary sedimentation tank in sequence from a wastewater inlet pipe and is discharged finally, wherein the microbial agent is added into the aerobic reinforcement tank. The microbial agent is applied to the treatment process of coking wastewater successfully, thus the removal rate of refractory organic matters can be increased significantly, the removal of COD, ammonia nitrogen and total nitrogen can be strengthened, the operation cost can be reduced greatly, and the treated wastewater can be up to the standard to be discharged.