According to the present invention, with the MEMS double-layer suspending microstructure production method, a suspending microstructure having double layers can be produced; and according to the infrared detector produced by using the double-layer suspending microstructure (having a first film body and a second film body), the second film body does not require the production of the cantilever beam, such that the size of the produced second film body can be larger than the size of the produced first film body to provide the larger suspending absorption area compared with the single-layer suspending microstructure so as to provide the high infrared response rate. In addition, the invention further discloses a MEMS infrared detector.