The invention discloses a plastic extension pipe and manufacturing method thereof. The plastic extension pipe is provided with a corrugated pipe body, both ends of which are integrally jointed with adapters, characterized in that viewed from the extended longitudinal section, the pipe wall presents a wave shape by ordinal alternant connections of a right side-wall, circular wave peak wall and a left side wall, curvature radius of the wave peak wall arc is 0.5 to 2 millimeters, a smooth transition is provided between the right side wall and the wave peak wall arc, a break point protruding to the inner pipe is formed by intersection of the left side wall and the wave peak wall arc. Manufacturing method includes steps of pipe blank extrusion moulding, pipe blank inflation forming in shaping mould and compression shaping. Advantages of the product are: good appearance, folding held facilitation and hard unpacking, strong self-shaping capability. Advantages of the method are: easy and simple, exact shaping and high rate of finished products. The product can be widely used as ventilation, exhaustion and drainage elements, for example super baths, ventilators, water channels, washing machines and smoke exhaust ventilators.