The invention discloses an interferometric phase microscopy one-step imaging system and method based on two-step phase shift, and adopts the technical scheme that based on a typical Mach-Zehnder interference light path, lateral displacement beam splitting mirrors are adopted to perform light splitting on sample light and reference light respectively, a wave plate is utilized as a phase shifter, and two interference figures can be acquired at the same time through single exposure, and phase imaging can be realized quickly through corresponding phase recovery operation, and a spatial form structure of a phase body is further deconstructed. The interferometric phase microscopy one-step imaging system and method are suitable for all interferometric phase microscopy imaging systems, such as traditional coaxial interference, off-axis interference and slight off-axis interference, and have high practical value and wide application prospect in the aspect of phase microscopy, particularly in the field of application and identification of biological cell morphology.