Abstract: By considering bolt slippage effect, three dimensional FEA model for a typical transmission tower body section was established in general software ANSYS. The member axial forces and the nodal deflections were separately calculated under vertical and horizontal loading. The effects of bolted joint type, load type and bolt slip distance on member axial forces and on nodal deflections were analyzed. For the vertical loading case, the bolt slippages between diagonal members and main members have a more significant effect on member axial forces and on nodal deflections. The axial force variations of the main member, the leg diagonal member and the inverse K diagonal member at the second segment are almost higher than those of the horizontal load case. For the horizontal load case, the variations of axial forces and nodal deflections are mainly induced by the bolt slippages between transverse separator members and main members. These bolt slippages have significant effects on the main member axial forces and on the horizontal nodal deflections near the loading points. The axial force variations of the main members and the diagonal members at the third segment are up to 34.8% and 45.2%, respectively. The bolt slippage distance has little effect on the maximum axial forces of main members and leg diagonal members. However, it has a significant effect on the vertical deflection at the loading point.