Because the tradition differential plane mirror interferometer (DPMI) has the disadvantages of complicated structure, many optical components and difficulty for adjusting, a novel differential plane mirror interferometer is proposed. Due to its diagonal symmetry of the two frequencies beams, this system has a good stability with environmental variation and a high resolution. With this special arrangement and the use of some additional optical components, the measurements of yaw angle, small rotation, straightness become easy to implement. Experimental result shows that the displacement drift of this system is under 1 nm in the static measurement, while the Michelson interferometer system is more than 10 nm under the same condition. The angular interferometer based on this new structure, with electronic interpolation of 2π/516, has a measurement resolution of 0.024 μrad.