Pure cement slurry has been used to plug leakage in drilling engineering. For the serious leakage, collapse and sticking in complex formations drilling, effective cement slurry and rational plugging technology must be used to prevent the loss of flushing fluid. The analysis is made on the performance variation of cement-clay slurry with bentonite, water glass and water reducing agent adding, and the optimized formulation of the cement-clay slurry is obtained, good effects have been received in the practical engineering project with higher drilling efficiency.