Abstract: To solve the defect of pile foundation of high buildings on karst foundation, this paper proposes a controllable pressure-tight grouting technology that uses low slump plastic concrete to reinforce the defect pile foundation. This technology uses a special high-pressure pump to form an effective pile diameter to improve pile foundation defects, which presses low slump with a strength of no less than 20 MPa and a slump of no more than 50mm into the strong karst development stratum. By means of in-situ tests and full-scale construction, a complete set of construction technology has been developed, which can be effectively applied to the treatment of bearing layer defects of pile foundation in limestone areas.