To improve the piling quality of the high-pressure rotary jet grouting pile at coastal tidal flats,we carry out piling tests in a cofferdam area with and without insertion of the drainage plate respectively of a land formation project in Shenzhen.Adjusting the water-cement ratio and mud pump pressure of double pipes technology and triple pipes technology respectively,we analyze the main factors affecting the pile formation of the high-pressure rotary jet pile in the soft foundation treatment of the mudflat layer of the tidal flats,summarize the main problems during pile formation construction,and propose reasonable solutions.The conclusion is drawn that the soft foundation treatment of the mud layer on the tidal flats should be constructed by the double pipes method.Before construction,drainage plates should be set up in the construction area,and a small water-cement ratio is preferred during construction.The application of the secondary spraying process can improve the pile formation quality effectively.