The invention relates to a centralized waste gas discharging method used in longitudinally ventilated road tunnel, which belongs to the road tunnel ventilation and fire-fighting field. The road tunnelcomprises an upward tunnel an a downward tunnel; The method comprises: disposing a pass-by duct on each tunnel near the tunnel portal to cause the airflow in one tunnel along the freight flow direction to flow into another tunnel through the pass-by duct; and arranging at least one centralized air-discharging well respectively inside the upward tunnel and the downward tunnel. The invention has the following advantages: solves the problem of addressing centralized air-discharge well in road tunnel, especially city tunnel; expands addressing range, develops tunnel ventilating and exhausting manners, and improves the tunnel construction feasibility of the section difficult for building wind well.