Abstract: Qingtongxia Hydropower Station has operated over 30 years. The inlet floors at sluiceway under water 32m are damaged by high-speed water flow with sand which influenced the safety operation of the power station. It is impossible to create the dry-site construction condition to repair the damaged areas owing to its special structure of power station. So a repairing scheme under water was developed and implemented using PBM polymer concrete to fill up the puddles and repair the floor. The desired result was achieved. It ensures safety operation of the station.