The depth of 1500m was designed for ZK3349 in Wuzhuang iron mine of Xuchang, where the thickness of overburden layer was up to more than 400m，there were several fracture zones, the contact zone of quaternary and tertiary strata with soft and hard interbedded rocks containing large amounts of gravel and boulder. Diameter shrinkage, wall collapse and hole inclination were often encountered. The corresponding measures were taken to smoothly fulfil the drilling. The open hole drilling in overburden layer and wire-line core drilling technology in deep hole are summarized.