The horizontal slice method is used to study the relation among the uplift capacity, the failure surface and soil parameters with Mohr-Coulomb failure criterion. According to the limit equilibrium approach, the uplift capacity is calculated by dividing soil around the pile into slices with regarding the potential failure surface as a group of several sectional planes. Then the multivariate function used to calculate uplift capacity is established and optimized by the sequential quadratic programming. Through the numerical calculation and comparison with the previous research, the results show that the method is reasonable and effective, and can be used to determine the failure surface shape and the magnitude of the uplift capacity of uplift piles.