Riverbed bottom sediment sampler

The invention discloses a riverbed bottom sediment sampler. The riverbed bottom sediment sampler comprises a base, a sampling tube and a sampling cylinder, a sampling groove is formed in the middle ofthe base, the base is provided with an inflating airbag, the inflating airbag is provided with an inflating opening, the sampling tube is connected into the sampling groove in an inserted mode, the lower end of the sampling tube is open to form a sampling opening, a sample accommodating cavity with the open side wall is limited in the sampling cylinder, the sampling cylinder is movably connectedto the lower end of the sampling tube in an inserted mode between the first position and the second position, when the sampling cylinder is located at the first position, the sampling cylinder is accommodated in the sampling tube, and when the sampling cylinder is located at the second position, the sampling cylinder extends out of the sampling tube from the sampling opening. Sinking and upward-floating of the base are con