Both Salix gordejevii and Caragana microphylla are dominant shrub species on moving and semi-moving dunes in Horqin Sandy Land which are well adapted to the arid and infertile condition. There is still poorly understand concerning the differences and dynamics on the sap flow and transpiration of the two shrub species. Dynamax Sap Flow Measuring System, Li-6400 Portable Photosynthesis System and Automatic Weather Station System were used to simultaneously measure and monitor the sap flow velocity, leaf transpiration and related environmental factors of the two shrubs. Based on the analysis of the diurnal variations of stem sap flow and leaf transpiration, the results showed that the diurnal variations of sap flow velocity of the two species were as a multi-peaked curve. The sap flow of Salix gordejevii and Caragana microphylla started at 4:30 and 5:30 while stopped at 20:30, respectively. The maximum value of the sap flow velocity of Salix gordejevii was 81.291.7 mg/h, and that of Caragana microphylla was 17.327.1 mg/h in field situation. The diurnal sap flow of unit cross-section area of stem of Salix gordejevii and Caragana microphylla were 0.881.56 g/cm² and 0.641.34 g/cm², respectively. The diurnal variation curves of the sap flow and the transpiration velocity of the two shrubs were non-synchronous to each other, which implied the dynamic variation of the sap flow could not be substituted by that of their the transpiration velocity. The leaf transpiration and the water assumption of Salix gordejevii were more than that of Caragana microphylla, which implied that the drought tolerance of the Salix gordejevii was lower than that of the Caragana microphylla. The sap flow density of the two species was positively correlated with some ambient environmental factors. The order of their coefficient from correlation analysis was ＰＡＲ (photosynthesis available radiation) ＞ air relative humidity ＞ air temperature ＞ wind speed ＞ soil temperature at 10cm depth ＞ soil temperature at 20cm depth. These results are of importance for clarifying the principle of plant’s water consumption and for explaining the adaptation processes and mechanisms of plants in arid and sandy environment.