Songbird is an ideal animal model for studying the mechanism of learning and memory of languages. The song system of zebra finches is highly sexually different. Uncover the mechanism underlying sexual-difference is important for the neural basis of birdsong. The role of single neuron on sexual-difference is rarely reported. Our current studies focus on RA single projection neurons. The active and passive electrophysiological properties were examined by cell attached patch or whole-cell patch recordings. We report here that the firing rate and peak amplitude of action potential in RA projection neurons in adult zebra finches are sexual dimorphism.