Abstract:The nano boron carbide particle size is 60 nm, dispersed in RO reverse osmosis membrane treatment water to form waterbased nanofluid by adding the dispersant. In experiment, the dispersant influence of sedimentation stability was investagetd, and three kinds of waterbased nano boron carbide fluid were prepared, with the mass fraction of nano particles at 06%, 08%, and 10%. By establishing a model of thinwalled hole, the waterbased nano hydraulic fluid flow field was simulated in thinwalled hole using FLUENT module of computer fluid dynamics (CFD) software, and velocity flow lines picture, velocity vector picture, and pressure variation graph were gotten by CFD postprocessing. The simulation results obtain that when the nano particle mass fraction of 08%, the prepared waterbased nano boron carbide as a hydraulic fluid transmission medium has good transmission performance.