The invention provides a shallow soil sampler drill bit and a soil-sampling method thereof. The shallow soil sampler drill bit comprises a drill rod joint, an exhausting part, a drill bit body and a soil-separating ring, wherein the drill rod joint is connected with a drill rod and a power device; the exhausting part is located at a joint of the drill bit body and the drill rod joint, namely, on a drilling shoulder position; the exhausting part has a function of exhausting air in the drill bit in a soil-drilling process while preventing external air from entering into the drill bit; the soil-separating ring is located at a tip of the drill bit. When the shallow soil sampler drill bit is used for sampling soil in a shallow layer, the shallow soil sampler drill bit has the advantages of high applicability, high efficiency, high core-sampling rate, small disturbance on soil sample and capability of effectively solving the problem of difficulty in sampling soft soil.