The invention provides a method for accelerating the synthesis of corynebacterium crenatum L-arginine through enhancing ammonia assimilation. Specifically, the yield of the corynebacterium crenatum SDNN403 L-arginine can be effectively improved through excessive co-expression of a glutamine synthase coding gene glnA and a glutamate dehydrogenase coding gene gdh of a key enzyme corynebacterium crenatum source of an ammonia assimilation way, and an aspartase coding gene aspA of an escherichia coli source in the corynebacterium crenatum SDNN403.