All guide kinematic pair of machine tools have three rotating degrees of freedom which include pitching angle, yaw angle and roll angle, in which the roll angle is mostly difficulty to measure for the producing reasons. The existing roll angle measurement interferometer is comprised of two symmetrical wedge prisms and two symmetrical wedge mirrors. A enhanced roll angle measurement interferometer which only uses one wedge prism and one wedge mirror is proposed. The proposed system uses less optical component and has implemented the same measurement resolution, which is more stability. The two beams with different frequencies are paralleled which is efficient for reducing the dead path errors and eliminating the cross talk of other freedom errors. By using the phase meter of which the resolution is 2π/512, the roll angle resolution of this system is 2 μrad.