The buried depth of the salt layer of well ChutTan 1 is 7106 ~ 7806.5 m, and the layer is Cambrian. No drilling fluid can be used for reference. The bottom hole temperature is 170 ℃, and fall-off, well leakage, rheological complexity will appear during the drilling process will. In this paper, the sulfonated lignite SMC substitution thinner is used to improve the flow pattern of the traditional unsaturated salt water under the conditions of high temperature and complexity in downhole, and the issue of “to add and to discharge” caused by strong dispersion and strong dependency resulted from dilution to deep well at later stage is solved. The functional nanoemulsion TYRF-1 is introduced. With the use of nanoemulsion characteristics, the nature of the interface of colloidal particles is changed so as to solve the problem of high temperature foaming, while enhancing the system lubrication performance. Then enhanced sealing is achieved by combining with composite asphalt at high softening point. The filter loss at high temperature and high pressure shall be controlled to solve the issue of borehole instability and fall-off; acid-soluble plugging agent SQD – 98, rigid plugging agent KGD- 1/2/3/4 are used at leakage section to avoid severe well leakage. The optimized drilling fluid system guarantees the drilling at salt layer of well ChuTan 1.