Accurate quantification of evapotranspiration and the analysis of its control factors are of vital importance for agricultural water conservation and ecological-environmental protection. The improved Shuttleworth-Wallace (S-W) model was introduced for simulating evapotranspiration and transpiration in drip-irrigated jujube (Ziziphus jujuba Mill.) orchards in arid areas. The simulations of the S-W model were verified against measured data obtained from the eddy covariance system and measurements of a pin-type stem flowmeter for two consecutive years. The relationships between evapotranspiration in jujube orchards and influencing factors were analyzed by using the structural equation model (SEM). The S-W model showed good performance in simulating evapotranspiration and transpiration in arid areas under parameter value with a1 of 6.9445, g0 of 0.0439, b2 of 4.6041, b3 of 957.1106, achieving root mean square error (RMSE) of 0.62~0.76 mm/d, regression coefficient (b) of 0.77~0.88, determination coefficient (R2) of 0.95~0.97, index of agreement (d) of 0.92~0.94, efficiency of simulation (EF) of 0.70~0.81, ratio of RMSE to observations standard deviation (RSR) of 0.44~0.55. The results of SEM indicated that six factors explained 84% and 89% of observed variations in soil evaporation and transpiration, respectively. The coefficient of influence of plant transpiration of soil evaporation was -0.70. Leaf area index had the highest effect on plant transpiration, with total influence coefficient of 0.52, followed by air temperature with total influence coefficient of 0.44 and no-indirect influence. Net radiation had the highest effect on soil evapotranspiration, followed by soil surface water content, with total influence coefficients of 0.50 and 0.49 and direct influence coefficients of 0.66 and 0.69, respectively. The results of this model confirmed that the S-W model can be served as an efficient tool for estimating evapotranspiration in jujube orchards in arid areas, whereas SEM may provide a perspective on agricultural water conservation in arid areas.