Neuromuscular junction consist of presynaptic membrane, synaptic cleft and postsynaptic membrane. In the neuromuscular junction, presynaptic membrane is the motor nerve terminal, have many synaptic vesicle. Postsynaptic membrane is the motor end plate of muscle fiber and the most striking structural features are the deep infolding of the sarcolemma. Between the nerve and muscle cells, there is a synaptic cleft of some 50-100nm. This review shows the ultrastructure and function of neuromuscular junction, summarizes the current knowledge.