As a typical cathodic coloring electrochromic material, molybdenum oxide has been widely exploited in the field of electrochromism due to its advantages such as simple preparation method, low cost, good cycling stability and electrochemical stability, etc. In particular, molybdenum oxide has a fast response and low biotoxicity, thus, it is very important and highly desired to study the electrochromic films and devices of molybdenum oxide. In the current review, the preparation methods of molybdenum oxide films, including physical vapor deposition method, chemical vapor deposition method, spray pyrolysis method, electrochemical deposition method,hydrothermal/solvothermal method, sol-gel method, LangmuirBlodgett deposition method and exfoliation and oxidation method are reviewed in detail. The advantages and disadvantages of various preparation technologies are also discussed. The effects of different doping elements on the molybdenum oxide films are summarized to improve the electrochromic properties. The research progress of molybdenum oxide electrochromic devices is further outlined. Finally, the existing problems of molybdenum oxide films and its devices in the field of electrochromism and the future research and application directions are discussed and prospected.