The invention provides a gas concentration field measurement method and device. The gas concentration field measurement method comprises the following steps: S1, a single beam emitted by a detection laser passes through a lattice stereoscopic grating and then projects a plurality of detection beams in a measurement space, the plurality of detection beams are reflected by a reflector, and the wavelength of the detection laser is that of an absorption line of a to-be-measured gas; S2, acquiring a detection light intensity which is the light intensity of all the detection beams reflected by the reflector; and S3, a concentration field of the to-be-measured gas is acquired according to the detection light intensity. According to the gas concentration field measurement method and device, the plurality of detection beams are formed in the measurement space through the lattice stereoscopic grating, and scanning equipment is not required to drive the laser to finish scanning of the measurementspace, so that the measurement cost is lowered, the measurement time is shortened, and quick real-time measurement of a gas concentration field is realized.