Nucleus Raphe Magnus (NRM) is a complex cell group. 5-HT, SP and ENK neurons in the NRM were identified by immunocytochemistry method. The afferent fibers containing 5-HT, SP, M-ENK, L-ENK, B-EP and SRIF were observed in NRM, the efferent fibers containing 5-HT, SP, ENK and TRH from NRM to spinal cord were studied. Two neurotransmitters (such as 5-HT with SP, ENK or TRH) were found in same neuron, fiber or vesicle. The neurons and axo-dendritic synapses of the NRM were analysed during Electroacupuncture (EA). The NRM increased their synaptic releases and the neurons were in active functional state during EA "Zusnanli". Studies show that NRM is one of important positions in EA analgesia.