In this paper, a 17 element linear array parallel scan compact millimeter wave focal plane array imaging system is realized by adding a scanning planar mirror and a fixed planar mirror in front of the improved reverse-microscope system, which is composed of an objective lens and an extended hemispherical lens. For improved reverse-microscope system (IRMS), the profile of objective lens is optimized to reduce aberrations and the field-of-view is extended to plusmn80, which is much larger than that of common reverse-microscope system (RMS). For incident wave with different incident angles, the contour diagrams of electric field in the focal plane of the imaging system are calculated by ray-tracing method and Stratton-Chu vector diffraction integral formula. The numerical results show that the 17 element linear array parallel scan imaging system has good imaging performance.