NOVELTY - Preparation of light hydrocarbons from natural gas comprises: combined reforming in which steam reforming of natural gas and carbon dioxide reforming of methane are carried out simultaneously in the presence of a nickel/alumina catalyst; Fischer-Tropsch reaction of carbon monoxide and hydrogen in the presence of a iron-copper-potassium (Fe-Cu-K)/zeolite catalyst to produce light hydrocarbons (2-4C) and methane and carbon dioxide as byproducts; and separation of the byproducts, methane and carbon dioxide, and recycling them to the combined reforming reaction.    USE - The process is useful for preparing light hydrocarbons (preferably light olefins) from natural gas, where the olefin is useful as a fundamental feedstock in the petrochemical industry.    ADVANTAGE - The yield of light hydrocarbons (2-4C) is 15-55 carbon mol.%, the yield of light olefins (2-4C) is 10-45 carbon mol.%, and the carbon monoxide conversion is 70-99 carbon mol.%. The process improves production yield of light hydrocarbons, thermal efficiency and carbon utilization efficiency. The catalyst shows stable selectivity and provides low deactivation rate. The process is cost-effective; and is an optimized process for providing light hydrocarbons. The catalyst has a good long-term stability and ensures a robust process for the production of light hydrocarbons from synthesis gas.    DETAILED DESCRIPTION - Preparation of light hydrocarbons from natural gas comprises: combined reforming in which steam reforming of natural gas and carbon dioxide reforming of methane are carried out simultaneously in the presence of a nickel/alumina catalyst, where the molar ratio of carbon monoxide and hydrogen is maintained at 1:1.5-2.5; Fischer-Tropsch reaction of carbon monoxide and hydrogen in the presence of a iron-copper-potassium (Fe-Cu-K)/zeolite catalyst to produce light hydrocarbons (2-4C) and methane and carbon dioxide as byproducts; and separation of the byproducts, methane and carbon dioxide, and recycling them to the combined reforming reaction.