In order to select the optimal dimension GFRP cloth for composite wood of timberwork, the mechanics of experimental samples made by China southern plantation were analyzed. The results showed that: GFRP reinforced the wood mechanical properties and the strength was affected by GFRP reinforcement ratio. However, it reduced the strength of internal bonding strength in a low range. As a result, the best dimension GFRP cloth was 145g/m2 grid cloth with grid size 5mm×5mm. moreover. The eucalyptus was fit to make for timberwork.