Based on the finite element method, a group of pile foundations composed of arrayed conductors are studied for the failure mode under vertical loads. The ultimate load capacity and rule of axial load transfer under different wellhead distances, pile numbers, pile diameters and pile lengths are analyzed. Combined with the structural characteristics of the conductor, the formula for calculating the group pile effect coefficient for conductor composite piles is derived. The research shows that: the pile group effect coefficient of the conductor pipe increases with the increase of the distance diameter ratio Sa / D1, decrease of the number of piles N, increase of the pile diameter D1 and increase of the undrained strength Su; the bearing capacity of the central pile increases with the pile length below the variable section L2. Compared with the ordinary steel pipe pile group foundation under the same working condition, the lateral friction resistance of the conductor composite pile group foundation is exerted more fully, and the group pile effect coefficient is higher.