Abstract:Aiming at the problems of low drilling efficiency and low coring efficiency of hard rock coring tools in ocean drilling， this paper introduces the basic development and land test of ?185mm hollow screw motor bottom hole power rope coring tool developed by the Institute of Exploration Techniques， CAGS. In the development process， through theoretical calculation and Ansys Workbench finite element simulation， the spiral structure of the hollow screw motor is optimized and the dynamic analysis is carried out. The force safety analysis of the universal joint is carried out， and the material is optimized. The key technologies such as multi-head small offset short pitch hollow rotor and flexible hollow universal joint are overcome. The feasibility of the working performance of the prototype of the coring tool is verified by the coring test of granite block on land， which provides the guidance of working parameters and the optimization of matching drill bit for the engineering application of this coring tool. It can provide hard rock coring technical support for ocean drilling and deep scientific drilling in China.