From April to December,2012,the sap flow of 10 years old E. urophylla plantations on the Leizhou Peninsula was continuously measured by the thermal dissipation probe(TDP).The results showed that the changes of sap flow had significant circadian rhythm.With the similar changes of intensity of solar radiation,there was a single peak on a sunny day and multi-peak on a rainy day.Compared with the solar radiation,the inflection changes of sap flow were lagging about 1 h.During the day,the sap flux of E.urophylla was significantly positively correlated with atmospheric temperature,wind speed,photosynthetically active radiation and vapor pressure deficit,and was significantly negatively correlated with the relative air humidity.At night,it was only significantly negatively correlated with the air relative humidity.There was no significant correlation with other environmental factors.During the observation period,the average daily water consumption per plant of 10-year-old E.urophylla Plantation was 28.03 L/d.The total stand transpiration water consumption was 963.3 mm,representing 58.61% of total precipitation during the same period.