The invention provides a vacuum holding type dejectas collecting system. The vacuum holding type dejectas collecting system comprises a first water tank, a second water tank, a third water tank, a fourth water tank, a squatting toilet, a sitting toilet, a grey water unit, a dining car water supply unit, a first sewage tank, a second sewage tank, a vacuum generator and a control unit, wherein sewage draining exits are formed in two ends of both the first sewage tank and the second sewage tank; washing water inlets are formed parallel to the sewage draining exits; and vacuum connections are arranged on the upper end surfaces of the first sewage tank and the second sewage tank so that the first sewage tank and the second sewage tank are connected with the vacuum generator. Due to the additionally arranged sewage tanks, the sewage and dirt are collected in the whole dejectas collecting system so that the dejectas collecting system has a very good protecting effect on the train operation surrounding environment and toilets of a train can be continuously used after arriving at stations. Due to the adoption of the vacuum holding type dejectas collecting system, the amount of water used to flush the toilets is greatly reduced so that water resources can be effectively saved and the flushing effect is improved.