The invention provides a drainage blind pipe and an assembly thereof. The drainage blind pipe is of a multilayer structure composed of an anti-crystallization coating, an inner wall drainage layer, an outer wall structure layer and a filtering layer from inside to outside. The interiors of the drainage blind pipe are connected through the assembly. According to the provided drainage blind pipe of the four-layer structure, the anti-crystallization coating can effectively prevent calcium carbonate and other crystals from being attached to the pipe wall, and pipe crystallization plugging is prevented; the inner wall and the outer wall adopt materials with different components and ratios, the material formula of the inner wall can enable the pipe wall smoothness to be high, the drainage capacity is improved, in addition, the stability is high, the acid resistance and the corrosion resistance are higher, and the weather resistance is also greatly improved; crystal whiskers, various solid fillers and multiple additives are added into the formula of the outer wall, the ring stiffness, the ring flexibility and other mechanical properties of the pipe can be effectively improved, and the flame resistance of the pipe is also improved; and the filtering layer can effectively prevent silt and other particles from entering the pipe, so that pipe silting is prevented.