In this work; based on the bubble theory, streamer discharge has been modeled and simulated in the water gap of 2.75mm length under the action atmospheric pressure. The streamer channels (plasma) were followed, at each time step. The simulation leads to the observation of growth, and branching of streamer channels between the two electrodes (pin – plane configuration). The results show that, the growth, and branching is dependent on the electric field distribution with the solution region. The streamer brides the water gap from anode (point) to cathode (plane) at a voltage of 17 kV. Also, increase the number of branches with the approaching to the cathode (plane). That indicates the streamer velocity increased with increasing the streamer time development. Generally, all values of the streamer characteristics increase with the increasing radius of the

Bubble Theory, Channel Radius, Streamer Theory.