the Jinchuan science deep drill preliminary guide hole is one project of the continental scientific drilling location and scientific drilling experiments of drilling. Design drill hole depth for 2000~2500 m, mainly adopts S122, S75 and S95 wire coring drilling technology. Considering deep drilling and small ring gap characteristic during wire core and the complex formation mine characteristics of Jinchuan, drilling fluid becomes an important technical design link. In this paper, the Jinchuan preliminary guide hole mud system and performance index of the design method are discussed, and researching the little ring gap and the cycle characteristics of the mud in deep hole and the wire core process adaptability in complex formation conditions; This paper also relates to the mining collapse and leakage formation of breast wall scheme in the plan design.