Limit equilibrium theory and variational method are combined to analyze ultimate uplift capacity of excavated foundation of transmission tower. A general shear failure for the soil mass around the tower is hypothesized. The soil stresses satisfy the yielding criteria of Mohr-Coulomb at limit conditions. The ultimate bearing capacities for different loading conditions can be estimated with this method. The effects of soil strength and embedment ratio on ultimate uplift of foundation under centric, eccentric and inclined uplift force are examined with a series of calculations. The influence coefficients of moment and horizontal force are proposed using a normalized processing. When the ratio of normalized moment to uplift force Nm is less than 0.4, the moment influence coefficient ? m declines rapidly with Nm. When Nm is more than 0.4, the decay rate of ? m becomes slow. Soil cohesion has more significant effects on ? m than the internal friction angle. The influence coefficient of horizontal loading ? h is affected by the soil strength and embedment depth simultaneously. The results show the values of ? h are smaller than those proposed in technical code. The accuracy and reasonableness of the method are verified by comparing test data with the results of formula in code. It can provide a reference for determining uplift capacity of outcrop foundations under eccentric uplift or horizontal force.