The invention discloses a shallow soil sample collecting device and a method for geological exploration. Pointed heads are arranged at bottom ends of supporting legs, so that position and direction stability of the collecting device is guaranteed; a distance measuring sensor is arranged on a supporting base, so that sampling depth is conveniently controlled; a sampling barrel can be used for performing layered storage on samples; a detecting hole is formed in a sample outlet sampling barrel; the sampling barrel is matched with a sample detector and a storage for use, so that samples can be preliminarily checked; samples are preliminarily sorted according to the checked results; and a triangular baffle plate can rotate for completely leading samples at each layer into sample slots from a sample outlet. The shallow soil sample collecting device is simple in structure, is convenient to operate, can quickly complete layered sampling and preliminary checking on a shallow soil sample, and isconvenient for follow-up analysis.