Abstract: Cementing plugging is a common operation in oil and gas field exploration and development, usually used in side tracking, backfilling and well abandonment. The quality of cementing plugging directly affects safety and environmental protection, with the basic requirement known as “pressing stably, sealing reliably”. The well A3 is a deep well in the Bohai Oilfield. During the drill process, drilling tool sticking and dropping occurred when the drilling depth reached 5046 m. After the failure of fishing, the only choice was well abandonment and side tracking. At that time, the bottom temperature exceeded 100 ℃, and the pore pressure was 1.52 g/cm3. There is a high total gas amount at this depth, and this well belongs to the low porosity and low permeability reservoir. Considering the failure of gas blocking by cementing plugging in previous operations, the combination of cement, floating beads, latex polymer and barite plug was proposed to block the gas. With the help of pressure waiting-on-cement, gas blocking was finally achieved, which guaranteed the safety of well control and subsequent operations.