Accidents happen a lot in excavation engineering because some key processes, such as anchoring boring, grouting, tension and draining hole, are not strictly controlled. Based on the analysis on the influencing factors of excavation instability and according to the stratum distribution characters in Changsha, introduction was made in the problems easily neglected in excavation construction and preliminary analysis was made on the feasibility and necessity of waterproof curtain. The paper summed up construction technology of pressure cycle grouting of anchor cable in aquifer.