Usually there is an inclined installation angle for an end-expanded ground anchor due to the requirement for soil layer selection, yet its influence on the pullout capacity of the ground anchor is not fully considered in the current practice. Based on the previous study and adopting the Mohr-Coulomb strength theory, expressions for the ultimate earth pressure on the expanded end and its pullout capacity were derived for an end-expanded ground anchor considering the inclined angle effect, and the relationship between the ultimate earth pressure on the expanded end and the inclined angle was explained under the conditions of different soil cohesions, angles of internal friction, and burial depths of the expanded end according to the basic mechanical mechanism. Research results show that the ultimate earth pressure on the expanded end decreased with increasing inclined angle in soil when the coefficient of earth pressure at rest was less than or equal to 1, and it increased with increasing inclined angle in soil when the coefficient of earth pressure at rest was larger than 1. The cohesion made the ultimate earth pressure on the expanded end less sensitive to the inclined angle due to its isotropic nature, while the angle of the internal friction and the burial depth of the expanded end made the ultimate earth pressure on the expanded end change in a complex way due to their anisotropic nature. For regular soils with coefficient of earth pressure at rest less than or equal to 1, the current practice in the specification that the pullout capacity of an inclined anchor practically adopts the one of the corresponding horizontal anchor may lead to unsafe design. The related expressions and rules can provide references for the design of anchoring engineering with end-expanded ground anchors.