Drilling depth-keeping underground water sampling device

The utility model discloses a drilling depth-keeping underground water sampling device, and relates to the technical field of underground water sampling devices, the drilling depth-keeping underground water sampling device comprises a sampling cylinder, a sampling rod is fixed in the sampling cylinder, a cylinder cover is slidably arranged on the sampling rod, a limiting block is fixed at the top end of the sampling rod, a spring sleeves the sampling rod, and the upper end of the spring is fixedly connected with the cylinder cover; the side face of the upper end of the sampling barrel is provided with an exhaust hole, the lower end of the sampling barrel is fixedly provided with a balancing weight, the side face of the lower end of the sampling barrel is provided with a water drainage hole, the position corresponding to the water drainage hole is provided with a threaded plug, the top of the sampling barrel is fixedly provided with a hook, and the inside of the hook is fixedly connected with a sampling rope.