The  thermal power plant is located at Thuy-nguyen District, Haiphong city in Vietnam with an installed capacity of 2×300 MW.  Since the power plant is located in a low land near the Gia River with developed Karst geomorphology and thick mucky soil strata on the top, the soil quality is too weak to meet the requirements of the foundation. Bored piles are planned to be used on the main construction area. Pile foundation test is performed in this project area. Mechanism of axial force transfer on the pile and the characteristics of load-settlement of the pile are analyzed. The results suggest that the ultimate bearing capacity of single pile could be 7000kN in this area. The axial force transfer on pile is influenced by many factors. Load on the pile top is transferred down gradually by lateral friction resistance which takes up a great proportion compared with the friction resistance on the pile end. Sediment thickness at the bottom of pile remarkably affects the pile top settlement and the ultimate bearing capacity of pile.