Along with the development of drilling technology, more and more complex stratum situations are encountered in deep and ultra-deep well drilling, and the demand of drilling fluid performance becomes higher. By the theoretical analysis and contrast on preparation methods of saltwater drilling fluid, according to the field application with existed salt resistant materials and based on the analysis and the tests on influence mechanism of pre-hydration to drilling fluid properties and influence of pre-hydration time to drilling fluid properties, it showed that the pre-hydration is very important to the performance of drilling fluid. With the changes of hydration time, drilling fluid property produces different changing trends. The analysis provides practical guide and theoretical basis to preparation of different drilling fluids with different emphasis points.