With the increasing depth of the oil and gas well and the increasing of geothermal drilling， the problem of high temperature drilling fluid is becoming more and more prominent. In the drilling process， it is very necessary to timely cool drilling fluid and make it reach the appropriate temperature for safety drilling. This paper summarizes the cooling ways and characteristics of the current frequently-used high temperature drilling fluid. In regard to the energy-saving characteristics of air cooling and the advantage of high cooling efficiency of the coolant with forced cooling， a high efficient cooling system for high temperature mud is put forward. The air cooler and the tube and shell heat exchanger in the cooling system are designed， checked and simulated， and the reliability of the design is also verified. As a result， the high temperature drilling fluid at 80 ℃ and 1800 L/min can be cooled below 40 ℃ using the cooling system. At the same time， the cooling effect at different drilling fluid temperature， different drilling fluid flow rate and different air temperature conditions is also discussed.