The geological structure is complex in Fujian coalfield with fault development, fractured and loose rock formations and thin sheet or muddy mudstone by being extrusion, which cause many difficulties for drilling; such as mud shale hydration expansion and severe hole collapse led by hole wall instability, etc. By the use of wire-line core drilling technology, optimum the diamond bit and scientific ratio of mud and drilling parameters, the technical difficulties in holes were successfully solved. The drilling efficiency is improved and the production cost is reduced.