【Objective】The aim of this study was to study the impacts of biochar addition on soil enzyme activities of farmland under global warming.【Method】Effects of warming and biochar addition on soil enzymes (urease,phosphatase,catalase and invertase) of farmland were examined using an in situ opentop Chamber (OTC) technique.【Results】OTCs increased average temperature by 0.96 ℃ but decreased soil water content. Moreover,biochar addition also significantly increased soil water content. Warming increased the activities of the soil phosphatase and invertase but inhibited the activities of urease and catalase. Biochar addition decreased the activities of urease,phosphatase and catalase. The urease, phosphatase,catalase and invertase activities were increased with increasing dose of biochar under the warming condition. Organic matter,pH,available phosphorus,available nitrogen and soil water content were main factors affecting soil enzymes activities. The path analysis showed that available nitrogen had a moderate effect on the activities of urease and catalase while the activities of phosphatase and invertase were significantly affected by soil pH.【Conclusion】Under the climate warming,biochar addition improved farmland soil environment,and consequently enhanced soil enzymes activity.