Sleeve floating coupling and well cementing method

The invention discloses a sleeve floating coupling and a well cementing method. The sleeve floating coupling comprises a tubular body, a blind flange and a retainer ring, wherein a first connection end and a second connecting end are respectively formed at the two ends of the tubular body, and a circular step and a circular groove are formed on the inner wall of the tubular body; the retainer ring is located in the circular groove; and the blind flange is located between the circular step and the retainer ring, and the blind flange is a brittle board which is broken into fine and small particles when impacted by 15-35 MPa hydraulic force. The well cementing method is implemented by adopting the sleeve floating coupling to carry out well cementing operation. By using the sleeve floating coupling, the well cementing process is simple and reliable to operate, thus the well cementing operation time and operation cost are greatly reduced, and the economic benefits are high.