NOVELTY - Preparing liquefied natural gas in-situ hydrogen, comprises (i) preheating water vapor and natural gas liquefied natural gas using heating output, mixing by contacting steam reforming catalyst with a reaction product gas, and reacting under pressure of 0.1-2 MPa, temperature of 450-1200 degrees C, space velocity of 500-5000/hour, and water-carbon ratio of 2-6; (ii) cooling of the product gas, and carbon monoxide shift catalyst reaction-shift gas, and reacting at a pressure 0.1-2 MPa at 300-500 degrees C, and airspeed of 500-2000/hour; and (iii) separating shift gas, and cooling.    USE - The liquefied natural gas in-situ hydrogen is useful for hydrogen fuel cell vehicles (claimed).    ADVANTAGE - The method does not require hydrogenation station and construction, and is economical.    DETAILED DESCRIPTION - Preparing liquefied natural gas in-situ hydrogen, comprises (i) preheating water vapor and natural gas liquefied natural gas using heating output, mixing by contacting steam reforming catalyst with a reaction product gas, and reacting under pressure of 0.1-2 MPa, temperature of 450-1200 degrees C, space velocity of 500-5000/hour, and water-carbon ratio of 2-6; (ii) cooling of the product gas, and carbon monoxide shift catalyst reaction-shift gas, and reacting at a pressure 0.1-2 MPa at 300-500 degrees C, and airspeed of 500-2000/hour; and (iii) separating shift gas using a purification membrane, to obtain hydrogen and carbon-monoxide content in the exhaust gas separation of less than or equal to 50 ppm, and cooling. An INDEPENDENT CLAIM is also included for a system comprising a water supply device, an air supply device, a steam conversion device, a carbon monoxide conversion device, a film separating and purifying hydrogen device, a cooling device and a hydrogen fuel cell, where the water supply device and the air supply device are respectively connected to vapor conversion device, and the vapor conversion device is connected to carbon monoxide conversion device, the carbon monoxide conversion device is connected to the film separating and purifying hydrogen device, the film separation and purifying hydrogen device is connected to the cooling device, the cooling device is connected to the and the hydrogen fuel cell, and water supply device includes a water storage and a heating device, and the heating device is connected to a water outlet of a reservoir, and the heating device is connected to steam conversion device, and the air supply device is set with an air bottle, forming a heater, and the steam conversion device includes a pre-heating module, a cooling module, a combustion heater and a reactor, and the reactor is tube-type fixed bed reactor, and the reaction tube is set on tubular fixed bed reactor used for depositing active component of vapor conversion catalyst, and an inlet module is respectively connected to pre-heating and water supply device and gas supply device, and an inlet and an outlet of reactor is set with a pre-heating component, and the inlet and outlet of reactor is connected to cooling module, and inlet and outlet of cooling module is connected to carbon monoxide conversion device, and an air supply device and/or cooling device are connected to a combustion heater by a fuel pipeline.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the system utilized in the above mentioned method (Drawing includes non-English language text).