Most of the seat parts of plastic inspection Wells are injection molded, and the fittings such as reducing joints, variable Angle joints and rubber seals are used to change the diameter and Angle of the pipe. The plastic inspection well is equipped with manhole cover, shaft and related accessories, and the road load acts on the inspection well around the well through the well cover and well seat, avoiding the damage of the road load on the inspection well. The well seat has the function of floating up and down, which can actively adapt to the change of the level of the road surface. At the same time, the shaft adopts a special shaft, which can intercept the corresponding length according to the buried depth of the site, which is flexible and convenient. The shaft, inlet (outlet) water pipe and well seat are connected by rubber sealing ring flexible socket connection or heat shrinkable sleeve connection, which can adapt to the Angle change in a small range, convenient and fast construction, good sealing performance, anti-leakage, and effectively prevent the secondary pollution of groundwater, which is a kind of environmental protection and energy saving building materials.