This paper introduces the worldwide application and research status of the drilling fluid additives with high -temperature and pollution re- sistance and drilling fluid systems based on the analysis on their crucial issues. It require increasingly high capacity of temperature resistance and ant/pol- lution to address the various down - hole problems encountered in the deep well and ultra - deep well drilling. The main technical difficulties include keeping their rheology, filtration loss and corrosion at a proper level. Drilling fluid systems possessing better temperature - and salt resistance against tem- perature 260 ℃ and relevant apparatus are the very direction of high temperature drilling fluid.