Abstract: The stem-flow of plant is one of the important plant physiological indices.In this paper, a calibration method for heat balance stem-flow sensor was proposed.According to the calibration experiment,the performance of stem-flow detection device was tested.The results showed that the value of sensor output was significantly correlated to stem-flow, (R2=0.96~0.97) with the resolution of 0.001 g/min and the precision of ±3%.Therefore, referring to the calibration experiment,the rate of stem-flow of plant can be accurately obtained,which can reflect the transpiration rate of plant and the information of moisture. It can provide an effective monitoring tool for the growth environment of plant and water-efficient irrigation .