NOVELTY - A direct thermal cracking generator comprises thermal cracking reaction chamber; combustion heating chamber provided below the thermal cracking reaction chamber; feeding hole provided on upper side of side wall of thermal cracking reaction chamber close to combustion heating chamber; gas supply pump provided below the combustion heating chamber; gas back burning pipe connected with gas outlet in upper part of thermal cracking reaction chamber; and air distribution and ignition device connected with combustion heating chamber.    USE - A direct thermal cracking generator for biomass (claimed).    ADVANTAGE - Combustible gas produced from cracking reaction is directly used as heat source for thermal cracking of biomass. The combustible gas directly heats up without burning thermal cracking raw materials in inner part of generator, thus improving heat efficiency. The method increases contact area of raw materials for heating in thermal cracking reaction chamber; enables raw materials to be completely mixed and thermally cracked; greatly improves reaction efficiency; and reduces pollution of harmful gases including carbon dioxide and soot dust while improving gas quality.    DETAILED DESCRIPTION - A direct thermal cracking generator comprises thermal cracking reaction chamber; combustion heating chamber provided below the thermal cracking reaction chamber; feeding hole provided on upper side of side wall of thermal cracking reaction chamber close to combustion heating chamber; gas supply pump provided below the combustion heating chamber; gas back burning pipe connected with gas outlet in upper part of thermal cracking reaction chamber; and air distribution and ignition device connected with combustion heating chamber. The gas back burning pipe is connected to combustion heating chamber by gas supply pump. Mixed materials comprising biomass raw materials and catalysts are transported to thermal cracking reaction chamber from feeding hopper. The mixed materials comprises 5-10 mass% catalyst i.e. calcium oxide, mixture of calcium oxide and magnesium oxide, nickel base catalyst or wood coal. The catalyst can be repeatedly used after recovery. An INDEPENDENT CLAIM is included for direct thermal cracking of biomass. The biomass raw materials are powdery. The produced carbon powder after thermal cracking directly reacts with carbon dioxide in back burning gases at high temperature to produce carbon monoxide. The thermal cracking reaction chamber temperature is maintained at 700-900 degrees C under normal pressure.