The invention relates to a containment vessel pressure relieving, filtering, and discharging comprehensive system. The system comprises a discharge pipeline for discharging air in a containment vessel. A first metal fiber filter is arranged on the section, which is in the containment vessel, of the discharge pipeline. After the discharge pipeline is leaded out from the containment vessel, the discharge pipeline penetrates an isolating valve of the containment vessel and is connected to a Venturi water washing filter. After the discharged air is filtered by the Venturi water washing filter, discharged air enters a second metal fiber filter. Condensate formed in the second metal fiber filter is returned to the Venturi water washing filter by a condensate returning pipeline. The air outlet end of the second metal fiber filter is connected to a silver-zeolite filter through a preheating loop. The air outlet end of the silver-zeolite filter is connected to a rupture disk. A downstream pipeline of the rupture disk is connected to a chimney of a nuclear power plant through a discharge isolating valve; or the downstream pipeline is returned to the interior of the containment vessel throughan air returning pipeline or is connected to a waste gas storage device. The system can guarantee the integrity of a containment vessel after a severe accident and ensures that no radioactive substance is discharged to the atmosphere and no person is damaged.