Abstract: Background Plant-based sand-fixing agent is a new type of environmentally friendly material with excellent water-holding and water-retention performance. Methods In this study, an indoor simulated evaporation test was conducted on soil samples treated with three plant-based sand-fixing agents (Artemisia argyi sand-fixing agent, flax sand-fixing agent, and Robinia pseudoacacia sand-fixing agent) and six different doses (0.5g/m2, 1.0g/m2, 2.0g/m2, 3.0g/m2, 4.0g/m2, and 5.0g/m2) on the surface. The same amount of pure water was sprayed as the control. By comparing the cumulative evaporation volume of different treatments after continuous evaporation for 30 days and through the fitting analysis of the Black and Rose evaporation models, the water retention effect of plant-based sand-fixing agents was further explored and their water-saving economic benefits were calculated. Results After continuous evaporation of three plant-based sand-fixing agents for 30 days, the cumulative evaporation of each treatment was significantly lower than that of CK. The flax sand-fixing agent had the most significant effect in inhibiting water evaporation, followed by the locust sand-fixing agent, and the sand wormwood sand-fixing agent was the weakest. The effects of the three sand-fixing agents on the soil evaporation rate of sandy farmland all show that the water retention effect is better when the application concentration is 2.0 g/m2 to 4.0g/m2. (2) The R2 of the Black evaporation model ranges from 0.951 to 0.999, while that of the Rose evaporation model ranges from 0.917 to 0.997. The Black model can more truly reflect the variation law of cumulative soil evaporation over time. The model fitting results show that the effect is better when the concentration of the sand-fixing agent is 1.0-4.0g/m², and R2 is all greater than 0.99. (3) The water-saving economic benefits of each treatment are as follows: flax sand-fixing agent (105,13 yuan/(10,000 mu · year)) > Artemisia sand-fixing agent (27,53 yuan/(10,000 mu · year)) ≈ Acacia sand-fixing agent (27,250 yuan/(10,000 mu · year)). conclusions Therefore, the application rate of 3g/m2 of flax sand-fixing agent can effectively reduce irrigation costs, enhance the water retention capacity and water-saving economic benefits of high-standard farmland, and is suitable for promotion and application in the construction of dryland sandy high-standard farmland in northwest China.