NOVELTY - Preparing natural gas from biomass material by thermal cracking comprises: (a) crushing material: crushing the material until the material reaches the required particle size; (b) drying material; (c) thermally cracking the material: bringing the material to a thermal cracking device and thermally cracking it in the absence of oxygen; and obtaining gaseous product; (d) separating it by cooling: separating the gaseous product by cooling to obtain flammable gas and liquid; and (e) separating it by compressing: separating the flammable gas by compressing to obtain directly utilized natural gas.    USE - The process and the thermal cracking furnace are useful for preparing natural gas from biomass material by thermal cracking (all claimed).    ADVANTAGE - In utilizing the process, more natural gas can be prepared and more heat values can be obtained. Moreover, it simplifies the construction of thermal cracking furnace by the oxygen-free thermal cracking environment, and it meets the energy required in the thermal cracking by only using an electric heater.    DETAILED DESCRIPTION - Preparing natural gas from biomass material by thermal cracking comprises: (a) crushing material: crushing the material until the material reaches the required particle size; (b) drying material: drying the material until the water content of the material is 0-12%; (c) thermally cracking the material: bringing the material to a thermal cracking device and thermally cracking it in the absence of oxygen; where the upper limit temperature of the thermal cracking is 400-1000 degrees C; and obtaining gaseous product; (d) separating it by cooling: separating the gaseous product by cooling to obtain flammable gas and liquid; and (e) separating it by compressing: separating the flammable gas by compressing to obtain directly utilized natural gas. An INDEPENDENT CLAIM is a thermal cracking furnace used for preparing natural gas from biomass material by thermal cracking, comprising a furnace body, a feed inlet on the upper part of the furnace body, and a gas outlet on the top of the furnace body; where the bottom of the furnace body is set with an electric heater.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the thermal cracking furnace used for preparing natural gas from biomass material by thermal cracking.