In view of the problems of high temperature，high formation pressure and easy lost circulation accident in Ledong block of South China Sea，a plugging slurry with a density of 2.4 g/cm3 was prepared by using composite plugging agent，inducer and suspension stabilizer. The component bearing strength，rheology，suspension stability and plugging effect of the slurry were studied. And the slurry was applied in Ledong block. The results showed that the strength of composite plugging agent and inducer was better，and the crushing rate was less than 25% at 220 ℃ and 50 MPa. The plugging slurry had good rheology，high temperature suspension stability and plugging effect. After aging at 180—220 ℃ for 16 h，the settling rate of the lost circulation slurry was less than 10% after standing for 24 h，and it could filter rapidly within 150 s at 0.69 MPa. When the particle size of sand stone was 4—10 mesh and 10—20 mesh，the percentage of plugging agent invading the sand bed was 65.6% and 52.3% respectively，and the bearing capacity was 10 MPa. After injecting plugging slurry into the wedge- shaped fractures with fracture width of 0.5，1 and 2 mm，a plugging layer with pressure bearing capacity of 10 MPa formed，and the reverse pressure bearing capacity was 7，6 and 6 MPa respectively. The plugging slurry was successfully applied on a well in Ledong block，showing good plugging effect