The invention discloses a biomass raw material-based polyurethane foam for fireproof thermal insulation boards, and a processing technology thereof, and belongs to the technical field of chemical engineering. The processing technology comprises the following steps: stirring and mixing a biomass liquefaction product, water, triethylenediamine, silicone oil and a catalyst, then adding crushed modified mixed biomass and an enzymatic chitosan liquid, stirring and reacting the above obtained mixture, adding castor oil, isoamyl acetate and modified graphene oxide, heating and reacting the obtained mixture, and sequentially carrying out injection molding, foaming, aging and demolding to obtain the biomass raw material-based polyurethane foam. Calcium oxide deposited in the crushed modified mixedbiomass reacts with water in the preparation process to make calcium ions merged in the system, and the calcium ions can promote the cross-linking of enzymatic chitosan to form a three-dimensional network, so alumina and iron oxide deposited in the system are immobilized, and the mechanical properties of the system are improved. The biomass raw material-based polyurethane foam provided by the invention has excellent mechanical properties and an excellent thermal insulation property.