The invention discloses an atomic spin precession detection method and device based on circular polarization detection light. The atomic spin precession detection method is based on spinning light characteristics of polarized atoms of an atom air chamber, left circular polarization light and right circular polarization light are formed through double refracted light paths, the left circular polarization light and the right circular polarization light are fed into the atom air chamber, phase position difference in direct proportion to atomic spin precession is generated from left spinning circular polarization light and right spinning circular polarization light of the air chamber, outgoing circular polarization light is fed back along the original path by using a reflection mirror, the left and right spinning directions of the left spinning circular polarization light and the right spinning circular polarization light are switched, the phase position difference is multiplied, the left spinning circular polarization light and the right spinning circular polarization light are interfered according to a circular polarization light interference technique, and thus phase position difference measurement and high-sensitivity detection on atomic spin precession detection are achieved. Atomic spin precession detection can be achieved, and the atomic spin precession detection device is high in precision, sensitivity, and anti-interference capability and small in size. The method and the device are practical, and super high in sensitivity and precision when provided for an atomic spin precession sensor based on atomic spin precession detection.