MOEMS gas sensing technology is an innovative technological solution for optical gas sensing techniques combined with MOEMS technology and new materials. MOEMS gas sensor has many advantages such as lower cost, higher integration, stronger anti-interference, higher test accuracy and so on. Firstly, the structure and working principle of primary optical gas sensing systems were introduced. Subsequently, the latest achievements, microoptical devices and microoptical system in MOEMS gas sensing technology were introduced. Taking the current research status of the MOEMS gas sensing devices as clue, challenges and priorities of MOEMS gas sensor were discussed.