In this study gypsum fiber board(GFB)was reinforced with wood fiber prepared by defibrator.The paper described the relationship between mechanical properties and wood/gypsum( W/G )ratio,water/gypsum( H/G )ratio and density was also established a mathematics models concerned.The results showed that MOR/MOE/IB increased significantly along with density increase; W/G ratio and H/G ratio were cross impacted,which had strong influence on board properties;both spring back and TS increased along with W/G increase;fiber pattern had significant effect on both IB and TS ;and defibering condition had little effect on MOR/MOE .