The relation between components, pressure, flow velocity and gain coefficient of CW OICL is theoretically analyzed by using a simple model throug digital computation. The operating region concerned is [O₂^*]/[I₂]=10~200,[O₂^*]/[O₂]=2~9,P=1~100 torr,U=5-100 m/s, The necessity of flow conservation equation for a CW OICL is detially discussed, It is shown that the available gain region will by enlarged proportionally to flow velocity while the peak gain value almost remains inveriable when flow velocity is increased.