The paper summarized the research actuality and application fields both in China and abroad. The design structure, specification and key techniques of QHZ-2000 casing rotator are elaborated. The paper analyzes the structure principle and the application characteristics of casing string, hammer grab and drilling tools for underground obstacles removal; and also summarizes the construction process, mechanism and applicable scope of full casing cast-in-place pile, underground obstacles removal and pile extraction in full casing. This study fills the gap of independent research and development of casing rotator in China; it is environmental, universal and safe piling equipment and a new foundation drilling method with no mud used in urban construction and foundation works.