A door assembly is provided which comprises a stationary frame and a movable frame, wherein the door assembly further comprises an adjusting assembly for fixing and adjusting the movable frame. The adjusting assembly comprises a fixing element disposed at one end of the fixing frame and including an engagement element on which a first groove is formed, an adjusting element disposed at one end of the movable frame and including a first through hole corresponding to the first groove and a cavity for receiving the engagement element, and a locking member comprising a handle portion and a rotation portion which can go through the first through hole such that at least one part of the rotation portion can reach in the first groove.