Bitter almond shell was pyrolyzed to prepare wood vinegar. The vinegar was studied in term of the antibacterial activity, physical characters and the chemical components, to offer the theory base for almond shell wood vinegar used as a botanic antiseptic. Based on pyrolysis theories, wood vinegars were collected rang from 90～170℃, 170～370℃, and 370～500℃ respectively, and refined by standing, adsorptions by charcoal and filtration. Physical and chemical characters were tested. Antibacterial activity of the obtained wood vinegar on germina was also investigated. The results showed that the generating temperature ranges of bitter almond shell wood vinegar is 90～500℃; the maximum amount of the wood vinegar was collected at the range of 170～370℃, which also showed the strongest anti-pathogens activities, the minimum pH and the highest organic acid content. GC/MS analysis showed that the main compositions of wood vinegar collected at 170～370℃ is hydroxybenzenes, organic acids, aldehydes, ketones, alcohols, furans and esters etc. Among all the components examined, the content of acetic acid was the highest (22.41%), next the furfural and the phenol. Based on the preliminary analysis, it was considered that phenols, acetic acid and furfural are the active components of antibacterial activity. 