Gas hydrate drilling in the Qinghai-Tibet Plateau permafrost bring into effect soon, the research about mud system is playing a important role. The article is through analysis the environment occurrence of gas hydrate in plateau permafrost and drilling enterprise technology features, characteristics of a low-temperature fluids theory as a guide, reference. the advanced experience of foreign countries, put forward a method about low-temperature mud system design based on inhibit decomposition methods. for the purpose, the research about the low-temperature mud system basis fluids is the key work to the implement the technology program. Paper have make detailed test to the three basis fluid which have better low-temperature inhibitory effect of salt brine, carbamate, organic alcohol ,have new understanding of the three basis fluid's solidification characteristics and rheological properties of change under the normal and low temperature, get the rules of the three basis fluid's solidification point with the concentration changes, laid a solid foundation to the research of low-temperature mud system.