As an important aerodynamic component in the upstream of the engine, the performance of the inlet has an important impact on the operating efficiency and capability of the whole aircraft. The geometric adjustment requirements of the inlet are elaborated firstly. The shortcomings of traditional mechanical adjustment methods as well as the promising application prospects of the shape memory alloy in morphing inlets are pointed out afterwards. The basic characteristics and typical aeronautical applications of shape memory alloy are then briefly introduced. At last, the progress of the applications of shape memory alloy in inlets is summarized, with special highlights of the SAMPSON program of the United States in the field of smart inlets.