NOVELTY - An alumina capillary column is prepared. Helium gas as carrier gas is passed to gas chromatograph, flow rate of helium gas is adjusted and the resulting mixture is subjected to flame-ionization detector. The sample cylinder is connected to sampling point of sample gas, valve is opened, air flow rate is adjusted, column is aged and cooled. The content of carbon in natural gas is calculated by determining the volume of component to-be-detected in natural gas, adsorption peaks of methane, ethane and propane, and detecting the volume fraction of methane, ethane and propane individually.    USE - Rapid detection of carbon content in natural gas (claimed).    ADVANTAGE - The method enables rapid detection of carbon content in natural gas with high precision, rapid analytical speed and low detection limit by simple and economical process.    DETAILED DESCRIPTION - An alumina capillary column having length of 50 m, inner diameter of 0.88 mm and film-thickness of 15 mu m is prepared. The purity of helium, hydrogen and nitrogen is tested to 99.99%. One end of sampling cylinder is connected to other end of pipeline of column chromatograph. The temperature of injector is adjusted to 50 degrees C and the temperature of detector is adjusted to 250 degrees C and column flow ratio is adjusted to 0.1 mL/minute. Helium gas as carrier gas is passed to gas chromatograph and flow rate of helium gas is adjusted to 30 mL/minute. When the temperature of helium gas is adjusted to 120 degrees C, the air valve or hydrogen pipeline valve is opened with air flow rate of 400 mL/minute and hydrogen flow rate of 35 mL/minute, and the resulting mixture is subjected to flame-ionization detector. The sample cylinder is connected to sampling point of sample gas, valve is opened, air flow rate is adjusted to 300-350 mL/minute, and the temperature of the furnace is adjusted to 200 degrees C. The column is aged at 200 degrees C for 2-3 hours and cooled to 40 degrees C. The content of carbon in natural gas is calculated by determining the volume of component to-be-detected in the natural gas, adsorption peaks of methane, ethane and propane, and detecting the volume fractions of methane, ethane and propane individually.