Process for comprehensive utilization of plant discarded matter

The process of comprehensively utilizing plant fibrous waste includes the following steps: depurating plant fibrous waste as material, cutting, drying, burning in a charring furnace at 200-400 deg.c, recovering the plant vinegar liquid with one recovering device connected to the charring furnace, recovering tar, discharging charred plant waste, cooling and recovering and treating the plant char. The present invention has reduced air pollution, high plant vinegar liquid recovering rate, and high plant char yield. The plant char may be used as soil improving agent and fertilizer and pesticide applying assistant.