Pile excavation damage often occur because of soft ground, especially in the regions along coast and river. Based on an engineering construction case of coastal power plant, by the statistical analysis on the data, this paper reveals the real reasons of pile foundation displacement, tilt and even broken while excavating. The excavation pile defects were found out by foundation pile core testing, ultrasonic testing and excavation validation. And according to the engineering case, it was put forward that reinforcement grouting methods could be taken for remedy and treatment, which was proved to be effective.