We report the preparation of a magnetorheological fluid with a high working temperature by using fluorocarbon surfactant and titanate coupling agent as additives at appropriate contents determined by a series of experiments. The sedimentation ratio, apparent viscosity, and yield stress are measured to evaluate the performance of the prepared magnetorheological fluid. Results indicate that AES dispersants, titanate coupling agents, and fluorocarbon surfactants all have improved dispersion properties, and that the compounding fluorocarbon surfactants and titanate coupling agent can further improve the settlement stability of magnetorheological fluid, with < 7 % one-week settlement rate. Diatomite has a good thixotropic effect, and the antisettling effect enhanced with increased content. The types of carrier fluid have no significant effect on the performance of MR fluids. The prepared MR fluid can also work at 180 °C, which is higher than most commercial fluids, and the shear yield stress can reach 50 kPa.