An adjustment-free multi-stage prosthesis air cylinder comprises an air cylinder body (2), a piston (3), a first check valve (4) and a multi-stage air pressure valve (1). The inner of the air cylinder body forms an air chamber (21) and a lower air way (22). One end of the piston is slidably disposed in the air chamber and divides the air chamber into an upper air chamber (211) and a lower air chamber (212), the other end of the piston extends to the outside； the inner of the piston forms an upper air way (31) which is communicated with the outside and the upper air chamber, while the lower air way is communicated with the lower air chamber. The piston makes a reciprocating movement in the air chamber, and the first check valve is disposed in the piston to optionally connect the upper air way with the lower air way. The multi-stage air pressure valve is disposed in the lower air way. With the arrangement of the multi-stage air pressure valve, the users can easily obtain different walking speeds without changing the air cylinder or setting the operational mode.一種使用於義肢關節的免調整之多段式義肢氣壓缸，包括一氣壓缸本體、一活塞件、一第一逆止閥及一多段式氣壓閥。氣壓缸本體內部形成一氣壓室及一下氣道。活塞件一端滑設於氣壓室內並將氣壓室分隔為一上氣室及一下氣室，活塞件另一端延伸至外部，活塞件內部形成一連通外部及上氣室的上氣道，下氣道則連通下氣室。活塞件在氣壓室內往復地移動，第一逆止閥設置於活塞件中以選擇地導通該上氣室及該下氣室。多段式氣壓閥設置於下氣道內。藉由多段式氣壓閥的設置，使用者不需更換氣壓缸，不必設定操作模式即可輕易應用於不同的行進速度。
