ABSTRACT The helix plate of the helical anchor can provide large uplift resistance for offshore floating structures. Although numerous studies have been conducted to estimate the uplift capacity factor of circular plate anchors in uniform clay, few studies have considered the effects of soil rigidity and shaft diameter on the uplift capacity factor. This paper studied the effects of soil rigidity and shaft diameter on the uplift capacity factor of shafted circular plate anchors in uniform clay through large deformation finite element analysis. The numerical analysis results showed that the increase in soil rigidity increased the uplift capacity factors. The increase in the shaft diameter ratio decreased the projected bearing area on the top of the circular plate anchor and uplift capacity factors. For the convenience of design engineers, a design process based on a conservative solution was proposed to estimate the uplift capacity factor of circular plate anchors.