The streamer regine of pin-to-plane dielectric barrier discharge in air was studied by means of fast photography,electrical measurement and photoelectricity.The fast photographs of positive streamer were obtained by CCD camera with micro lens.The exposure time is one microseconds.The images illustrate that the streamer is non-axisymmetric because of some random factors,such as surface charge position,space charge distribution,gas liquidity and so on.In fact,the streamer propagates along bend discharge channel.