The invention discloses a gravity-type anti-toppling sediment depth measuring device and a using method and belongs to the field of measuring and control technology and underwater sediment detection.The device comprises a detection head at the lowest end, multiple combined mechanisms in the middle and a cable connector at the upmost end, the number of the combined mechanisms is set according to needs, and each combined mechanism comprises a sample protection outer pipe, a detection rod, a detection rod inner core, a positioning pipe hoop, a resetting spring and a connection sleeve; between two combined mechanisms, the top ends of the connection sleeves and the lower ends of the detection rods are in threaded connection. A sediment sample is retained in a sampling hole in the detection rodand serves as a basis of sediment thickness measuring, and a sediment protection mechanism of the device is of a sleeve structure, so that the sediment sample is avoided being scoured while interference of water resistance on vertical posture of an instruction during lowering is avoided; the detection rod inner core is of a structure with lighter end up, so that toppling of the instrument duringlowering is prevented. The device is simple and convenient to operate, efficient and visual in measuring, good in anti-toppling effect, simple in structure and low in cost.