Aluminum angles are widely used as tension members with bolted connection in buildings. In current design specification for net tensile capacity, reduction factor (U) is usually used to account for the effects of shear lag and bending induced from load eccentricity. In this paper, an investigation on reduction factor (U) of bolted angle connections was conducted and focused on net section efficiency according to the change of plate thickness and bolt arrangement. Exception to some specimens with short end distance and 1x1 bolt arrangement, all most specimens failed by net tensile fracture accompanied by curling at outstanding leg. The value of curling deformation has increased with increase of end distance (e) and the curling influenced the fracture mode of bolted angle connection. Also, net section efficiency has tended to increase according to the increase of bolt number and plate thickness.