N2gas discharge fluid model is built by employing the continuity equation-the Poisson’s equation and the model is worked out by using finite element method． Thus obtained is the particle dynamics property of the narrow-gap ( 5 mm) N2during its discharge process． Through imitating the N2gas discharge process，the authorfinds that in a uniform field，the space electric field and electrons density and ions density at the tip of the streamerincrease with the propagation of negative streamer; when the ionization density in the initial hemispheroid increase，the space electrons density and electric field at the tip of streamer increase． The propagation velocity and othercharacteristics of the streamer are influenced by the diameter of the initial charge distribution． For negative stream-er，the ionization density and electron density gradient and electric field at the tip increase with increasing appliedfield．