Drilling fluid additives has a major impact on rheology behavior and other performances of the drilling fluid. The key to low temperature drilling fluids is choosing antifreeze and polymer agent which have a strong ability in resisting low temperature. On the basis of determining glycol as antifreeze agent, the low-temperature-performance and capacities of anti-collapse of regular validitymud agents have been studied, the mechanism of anti-caving of the partially hydrolyzed polyacrylamide ( PHPA) , polyp ropylene potassium (KPA) and PAC-141 polymer additives have been also analyzed. A pilot study of compatibility between ethylene glycol and the poly- mers has educed that the polymers, ethylene glycol and inorganic salt are compatible, and they can significantly reduce the freezing point of drilling fluid. Anti-collapse ability of the drilling mud is the results of synergistic action among the agents.