The invention provides a sampling and pretreatment device of redox sensitive element containing water. The device comprises a tank, a pull rod, a cover and a piston, a center hole is formed in the center of the top of the tank, a water filter pipe is arranged outside the center of the bottom of the tank, a filter membrane is arranged on the inner side of the center of the bottom of the tank, a shutoff valve is arranged on the water filter pipe, and a pipe opening of the water filter pipe is covered with the filter membrane. A sampling pipe is arranged at the bottom of the side wall of the tank, a water outlet pipe is arranged at the bottom of the sampling pipe, a three-way valve is arranged at the intersection portion of the water outlet pipe and the sampling pipe, the pull rod is sleeved with the tank, the top of the pull rod stretches out of the center hole, and a through shaft core is arranged in the axial center of the pull rod. The piston is connected with the bottom of the pull rod, a through hole is formed in the axial center of the piston, the through hole corresponds to the shaft core, and the cover and the top of the pull rod are connected in a configured mode. According to the sampling and pretreatment device, it can be avoided that redox sensitive elements are in contact with air to generate chemical changes in the water sample collecting process, the authenticity of water samples is guaranteed, the sampling device is directly utilized for suction filtration, cost is reduced, time is saved, efficiency is improved, dividing sampling is achieved, and flexibility and convenience are achieved.