The invention discloses a laser self-mixing multi-physical parameter measurement method and a laser self-mixing multi-physical parameter measurement device for an atmospheric particulate. The laser self-mixing multi-physical parameter measurement device comprises a microchip laser, a collimating lens, a beam splitter, converging lenses, a photodetector, an amplifier, a data acquisition card and a spectrum analyzer. Laser emitted by the microchip laser is focused onto the atmospheric particulate to be measured through the collimating lens and the converging lens, and part of generated backwards-scattered light is fed back to the laser due to the reversibility principle of an optical path, so that parameters such as power and wavelength of the laser are changed, namely a laser self-mixing effect is achieved. In addition, the beam splitter is additionally arranged in the optical path to split a small part of laser beam for the photodetector to receive, and a laser self-mixing signal is acquired and analyzed by the amplifier, the data acquisition card and the spectrum analyzer. The laser self-mixing multi-physical parameter measurement device has a simple structure, and is easy to regulate; and the detection accuracy of an atmospheric particulate detection device is effectively improved.