The fast urban greening in the arid and semi-arid lands in temperate and tropical regions increased the consumption of water resource greatly. Identifying the characteristics of tree transpiration, as well as the environmental and biological variables controlling water use in urban environment can help us choose the reasonable tree species and manage them scientifically. Magnolia liliflora is a typical urban greening species and distributes widely due to its high ornamental value. However, the water use characteristics of M.liliflora in the urban environment are poorly understood. Thermal dissipation method therefore was used to quantify the sap flow variations of M.liliflora trees at multi-temporal scales. The environmental factors including total radiation (R_s), vapor pressure deficit (D), air temperature (T_a), air humidity (RH), soil water content at the depth of 10cm, 30cm, 50 cm, 80 cm (SWC₁₀, SWC₃₀, SWC₅₀, SWC₈₀), wind speed (w) and precipitation (P) were also monitored at the same frequency as sap flow measurement. Sapwood cross-sectional area (A_S, cm²) was estimated from increment borer samples. Sap flux density measurements made in stems were scaled to each individual tree by its A_S. Measurements of whole-tree leaf area index (LAI) were measured using a Plant Canopy Analyzer (LAI2000, USA) every two or three days during leaf expansion and defoliation, and once a week in other period under diffuse light conditions on cloudy days or at dusk. The diurnal, daily, monthly and seasonal variations of whole-tree sap flow were analyzed. Diurnal sap flux density (J_s) of M.liliflora had the double peak pattern in spring and summer and single peak pattern in autumn. The monthly variation of the whole tree transpiration (E_t) increased gradually from March to May and decreased rapidly after September. The seasonal variation of E_t was the highest in spring and decreased in the sequence of summer, autumn, winter. Changes in plant phenologyphase directly related to the change of E_t. E_t rose rapidly from sprouting stage to flowering and leaf expansion stage, reached the maximum value in the fast growing period and the minimum value in the dominant period. Great variations in E_t observed at different temporal scale were due to environmental factor changes. On the diurnal scale, hourly mean J_s with significant time lag was significantly related to R_s and D (R²＝0.87, P<0.001; R²=0.66, P<0.001). On the daily scale, E_t significantly related to R_s, T_a, and D, while there were no obvious relationships between E_t and SWC due to the irrigation and amplitude rainfall during the research period. On the monthly scale, T_a was the most important factor affecting E_t. During the flowering and leaf expansion stage, LAI was the most important factor affecting E_t, while the environmental factors only explained 25.5% variance.