The invention provides a three-field of view digital holography detection device and a method based on a two-dimensional phase grating and point diffraction. The device comprises a light source (1) with an emergent wavelength to be lambda, a first polarizer (2), a collimating beam expansion device (3), a measurement window (4), a to-be-detected object (5), a first lens (6), the two-dimensional phase grating (7), a hole array (8), a second polarizer (9), a third polarizer (10), a fourth polarizer (11), a second lens (12), a diaphragm (13), an image sensor (14) and a computer (15). Field of view translation and frequency domain separation are realized through two-dimensional phase grating splitting and carrier introduction, interference of three object light beams can be avoided through the polarizer group, and reduction of crosstalk between spectra is realized. The method is simple and easy to operate, the adjustment is convenient, and the field of view use rate of the image sensor is high; a hologram carrier frequency mapping relation is simple, accurate control can be realized through grating defocus, the system carrier frequency determination complexity is low, and the phase recovery algorithm efficiency is high.