Well ZKX is located in the salt bed of Yexian with the purpose of the salt mine survey in Yexian-Wuyang depression of Henan. The planned depth of the wellbore was 2630 m, and the continuous coring was operated from 2000 to 2400m. Mainly the sedimentary strata of mud shale, sandstone, and the salt rocks were drilled; there were difficulties in anti-sloughing, core protection and wellbore stability in drilling construction. On the basis of the optimization of the drilling fluid system and according to the different strata, the anti sloughing drilling fluid system, unsaturated salt water drilling fluid system and saturated salt water drilling fluid system were used respectively, which solves the technical difficulties of anti-sloughing in water sensitive shale and problems of drilling fluid for continuous coring in halite stratum. A set of technical ideas has been explored for low cost drilling fluid which is suitable to core drilling in salt bed.