The invention discloses a multi-probe flatness detector and a corresponding flatness detection method. The multi-probe flatness detector comprises a measurement probe array, a measurement objective, an interference microscope, a charge coupled device (CCD) imaging device, a vertical scanning working table and a horizontal working table, wherein the interference microscope and the CCD imaging device are arranged on the vertical scanning working table and respectively used for forming interference fringes of light and imaging the interference fringes; the measurement probe array comprises a plurality of probes; a probe tip is arranged at the front end of each probe, and a flat reflecting mirror is arranged at the rear end of each probe; the measurement objective is fixedly arranged on the lower part of the interference microscope, positioned above the flat reflecting mirrors of the probes and used for gathering light rays; and the horizontal working table is arranged below the measurement probe array and used for placing a sample to be measured. According to the invention, multi-probe simultaneous measurement can be realized, the characteristic of high accuracy of light interference is fully utilized, influence of the optical performance of a measured surface material during measurement is effectively avoided, and effects of simple structure, high measurement accuracy and low cost can be correspondingly achieved.