Abstract: This study investigated the effects of zinc borate (ZB) on the physical, mechanical and decay-resistant properties of poplar oriented strandboard (OSB) panels bonded with phenolformaldehyde (PF) and diphenylmethane diisocyanate (MDI) resins. ZB was added at three loading levels, being 0.5%, 1.0 % and 3.0%, onto the dried strands during blending. The results indicated that physical and mechanical properties of poplar OSB panels containing ZB met the requirements for OSB/3 according to China standard LY/T 1580—2000, and decay resistantance of those panels was highly improved compared with the control panels. Addition of 0.5% ZB did not have detrimental effects on the physical and mechanical properties of OSB panels bonded with PF and MDI resins. Mechanical properties of OSB panels bonded with MDI decreased with the increase of the ZB loading level from 0.5% to 3.0%. At the same loading level of ZB and resin content, panels bonded with MDI had better mechanical properties than those bonded with PF resin.