• A novel analytic method for plum blossom pile skin friction is developed, incorporating cross-sectional geometry and vertical shearing effects.
• The method accurately predicts skin friction, negative skin friction, axial force, and dragload, validated against FEM and literature.
• Increasing the shear action coefficient reduces axial force along the pile depth under vertical load.
• The study provides a design tool for plum blossom piles, enhancing bearing capacity through perimeter enlargement.