Abstract: Current codes at home and abroad have unclear regulations on the analysis method of anchor bolt tension when the post-anchor connection is subjected to multi-directional loads. Based on existing research on rigid baseplate under uniaxial bending, a theoretical calculation method of anchor tension under biaxial bending is proposed first. In order to consider the influence of the elastic deformation of the baseplate on the anchor force, a finite element analysis method is proposed by establishing a simplified numerical model of the post-anchored connection joint. The accuracy of the method is verified through a comparison with the test results. Two types of baseplate assumptions were used to analyze the tensile forces of group anchors for three typical examples. It is found that the out-of-plane bending deformation of the baseplate increases the maximum tensile force of the anchor by 37%, 39%, and 85%, respectively, and the total tensile force of the group anchors is increased by 9%, 27%, and 40%, respectively, bringing significant safety hazards to anchor nodes. The amplification coefficient of the baseplate deformation to the maximum anchor tension force and the amplification coefficient of the total tension of the group anchor are proposed respectively, the influencing factors are analyzed, and the prediction equation is proposed based on the method of multiple linear regression. The research results in this paper can provide supplement and reference for the calculation method of anchor tension in existing specifications of post-anchored technology, and provide theoretical basis for the independent development of anchor design software in China.