The invention discloses a purging and trapping device of VOCs (volatile organic chemicals) in water and a purging and trapping method using the purging and trapping device. The purging and trapping device comprises a mixed gas carrying gas inlet, a purging pipe, a pure gas carrying gas inlet, a dehydration device, a cyclone separator and an enrichment separation device, wherein the mixed gas carrying gas inlet is connected with one end of the purging pipe; the other end of the purging pipe is connected with a water sample inlet and outlet and a purging gas outlet and is connected with the puregas carrying gas inlet and the dehydration device through a three-way valve; the cyclone separator is arranged between the dehydration device and the enrichment separation device; the tail end of theenrichment separation device is connected with a detector. The purging and trapping device has the advantages that the purging and trapping efficiency can be improved; the gas carrying consumption isreduced; the time is shortened. The mixed gas is used for purging, the mass transferring speed of the VOCs between liquid and gas is accelerated; the purging and trapping rate on the VOCs in water isincreased; the detection limit of the VOCs is improved; the evaporation quantity of water vapor can be reduced; the next water removal, trapping and detection is facilitated.