We used a threshold controlling method to control chaos of chaotic neuron and constructed a threshold coupled chaotic neuronal map. The synchronization of the threshold coupled chaotic neuronal map was investigated. Simulation results show that the value of threshold determines the temporal period of outputs of the threshold coupled chaotic neuronal map. The spatial behavior of outputs of the threshold coupled chaotic neuronal map is determined by a relaxation time. A cluster character exists in the threshold coupled chaotic neuronal map. The synchronization of outputs of the threshold coupled chaotic neuronal map is achieved if the relaxation time is big enough.