An acceleration sensing structure includes a frame, a proof mass, a gimbal and at least two outer flexible arms. The proof mass is suspended from the frame and has a first thickness. The proof mass is surrounded by and connected to the gimbal. The gimbal has a second thickness. The at least two outer flexible arms are connected between the gimbal and the frame, and the at least two outer flexible arms are arranged symmetrically. The second thickness is larger than or equal to one-half of the first thickness and is smaller than or equal to the first thickness, and when the proof mass moves, the at least two outer flexible arms are deformed. |