Abstract: Combined with the engineering geological feature of the red bed in West Yunnan, this paper conducts tests and researches on the characteristics of bearing capacity of pile foundation under different construction conditions. The relevant factors influencing the characteristics of bearing capacity of pile foundation for the red bed in West Yunnan are analyzed. Through the analyses of loading test using mortar casting around pile to harden soil and water injection around pile to soften soil, the result shows that mortar casting can increase greatly the bearing capacity of pile while water injection can reduce the bearing capacity of pile. The findings may provide reliable evidence to the design and construction of pile foundation in the area of red bed in West Yunnan.