NOVELTY - A one-step pressure swing adsorption hydrogen-purifying device comprises a first adsorption tower, second adsorption tower, first three-way piece, first pressure gauge, first reversing valve, second reversing valve, second three-way piece, third reversing valve, second pressure gauge, third three-way piece, fourth reversing valve, fourth three-way piece, fifth reversing valve, sixth reversing valve, raw gas tank, vacuum pump and hydrogen collecting tank. An outlet of raw gas tank is connected with one ends of both second and fifth reversing valves.    USE - A one-step pressure swing adsorption hydrogen-purifying device for supplying hydrogen gas (H2) to fuel cell.    ADVANTAGE - When a hydrogen-rich gas flows through a pressure swing adsorption device, carbon monoxide (CO), methane, carbon dioxide and water can be removed by the three adsorbents in one step. Since the device has two towers to perform the pressure swing adsorption, i.e. pressurized adsorption and pressure-reduced adsorption are performed at the same time, the H2 can be produced continuously. The device processes foreign gas in one step, thus shortening purification process. A content of CO is less than 10x 10-6. An operation is simple and the power consumption is low. The device can supply high purity H2 to fuel cell for direct use.    DETAILED DESCRIPTION - A one-step pressure swing adsorption hydrogen-purifying device comprises a first adsorption tower, second adsorption tower, first three-way piece, first pressure gauge, first reversing valve, second reversing valve, second three-way piece, third reversing valve, second pressure gauge, third three-way piece, fourth reversing valve, fourth three-way piece, fifth reversing valve, sixth reversing valve, raw gas tank, vacuum pump and hydrogen collecting tank. An outlet of raw gas tank is connected with one ends of both second and fifth reversing valves. Other end of second reversing valve is connected with lower end port of first adsorption tower and one end of third reversing valve through the second three-way piece, respectively. The other end of fifth reversing valve is connected with lower end port of second adsorption tower and one end of sixth reversing valve through the fourth three-way piece, respectively. The other ends of both third and sixth reversing valves are connected with inlet of vacuum pump. An outlet of vacuum pump is vented to the air. An upper end port of first adsorption tower is connected with one end of firth reversing valve through one end of first three-way piece. An upper end port of second adsorption tower is connected with one end of fourth reversing valve through one end of third three-way piece. Other ends of both first and fourth reversing valves are connected with hydrogen collecting tank. An outlet of hydrogen collecting tank is connected with a fuel cell system. The first pressure gauge and second pressure gauge are arranged in first three-way piece and third three-way piece, respectively.