A light-weight bacteriostatic building thermal-insulation material is disclosed. The thermal-insulation material is prepared from, by weight, a proper amount of polyvinylpyrrolidone, 100-120 parts of an aqueous silver nitrate solution having a concentration of 3-5%, 27-30 parts of ethyl orthosilicate, 3-4 parts of sericin, 2-3 parts of tributyltetradecylphosphonium chloride, 1-2 parts of pentaerythritol, a proper amount of ammonia water, 0.4-1 part of divinyl benzene, 0.2-0.3 part of Span 80, 3-5 parts of 1,3,5-triglycidyl isocyanurate, 180-200 parts of styrene, 0.1-0.2 part of hexadecyldimethylamine, 7-10 parts of ammonium persulfate, 5-6 parts of stannous octoate, 16-20 parts of a pentane foaming agent, a proper amount of glycol and a proper amount of dimethylformamide. The thermal-insulation material has good flame retardance, thermal insulation performance, bacteriostatic performance, and a light weight, and is convenient to mount and transport.