An architectural wooden bar unearthed in Hemudu,Yuyao,Zhejiang Province has suffered from disintegration caused by micro organisms after earlier replacement and filling with polyethylene glycol (PEG).The antimicrobial effects of chitooligo saccharide,catechin and zinc oxide nanoparticles on those ancient wooden structures were tested,with the aim of avoiding the environmental issue resulting from synthetic preservatives.The classical method of separation and identification of destructive microbes was used,and the effective antimicrobial concentrations of chitooligo saccharide,catechin,and zinc oxide nanoparticles were investigated.The bacteria which damage ancient soft timber include Pseudomonas aeruginosa,Morganella morganii and Flavabacterium oboratum.Fungi include mainly Trichoderma lignorum,Aspergillus terreus,Aspergillus glaucus,Penicillium chrysogenum and Rhizoctonia solani;The primary bacterium that damage ancient hard timber is Presumptive Acinetibacter lwoffii,fungi include Trichoderma koningii,Phialophora richardsial, Penicillium chrysogenum,Penicillum patulum,Cephalosporium costantinii,Alternaria tenuis and Rhizoctonia solani.The respective effective antimicrobial concentrations of chitooligo saccharide,catechin,and zinc oxide nanoparticles are 2.5%,10.0% and 5.0%.The effectiveness of 10% catechin's against the four main types of destructive bacteria is greater than that of 2.5% chitooligo saccharide and 5.0% zinc oxide nanoparticles;the inhibitory effect of 2.5% chitooligo saccharide toward eight kinds of filamentous fungi is greater than that of 10.0% catechin and 5.0% zinc oxide nanoparticles.Since chitooligo saccharide,catechin and zinc oxide nanoparticles show selective inhibitory effects against ancient timber microbes,and taking into account that the main harmful microbes to timber is fungi,2.5% chitooligo saccharide is the preferred environment friendly bio antibacterial agent.