Small-diameter deep water sampler

The utility model relates to a small-diameter deep water sampler. A sampler body is made of a stainless steel tube, a water inlet hole is arranged on the upper tube wall of the sampler, a non-return diaphragm valve is arranged inside the water inlet hole, a seal cover is arranged outside the water inlet hole, one end of the seal cover is fixed to the middle section of a movable arm, the lower end of the movable arm is movably connected to a support, the support is fixed below the water inlet hole, a mould spring is further arranged on a tube arm below the support and connected with the movable arm, the upper end of the movable arm contacts with a slope of a sloped slider (3) capable of vertically sliding and mounted on the tube arm, and when the sloped slider slides down, the upper end of the movable arm can be raised up so that the seal cover connected with the movable arm is opened. A water outlet of the sampler is arranged at the bottom and controlled by a water outlet valve. A rope clamp for fixing a test rope is arranged on the sampler. The small-diameter deep water sampler has the advantages of simplicity in operation, reliable performance and high success rate of water sampling.