Abstract: Dongjiang drilling and blasting tunnel crossing Guangzhou-Shenzhen branch at east section of the 2nd West-to-East Gas Pipeline is a controlling project. Underwater drilling and blasting method is adopted in this project, so water detection, prevention and control during the construction are essential for the safety and success of the project. Based on its characteristics, a series of methods are adopted in Dongjiang tunnel project, including long-hole advanced detection, short-hole advanced detection, long-hole high pressure curtain grouting, fixed point grouting, and short-hole fixed point grouting. In this way, the water is intercepted outside tunnel excavation borderline and water production is kept in controllable range. Large-scale collapse and roof falling are prevented by means of pre-grouting surrounding rock consolidation, short-distance excavating and supporting and combined support. Therefore, the tunnel is put into operation smoothly. It provides rich experience and reference for similar projects.