Marine reefer containers may transport goods at their different best temperatures to any port in the world in a rapid, safe, flexible and economical way, so it has become the most important new means of transport in the international trade. However, during the ocean going transportation, influenced by such changing interference factors as navigation area, solar radiation angle, air and water temperature, reefer containers work under complex and adverse conditions in a long time, so reefer container faults and cargo damage take place frequently. Coupled with increasing types of cargo, only to rely on manual inspections and on-site diagnosis is not only inefficient but also ineffective. Thus, it has put forward higher requirements on the condition monitoring and fault diagnosis system of ocean going reefer containers. In the paper, a data wireless transmission and condition monitoring system of marine reefer containers based on the serial communication interface is designed and a remote monitoring and fault diagnosis system based on Inmarsat F is put forward. With its application to the ocean going ships, it will undoubtedly have great practical significance to the safety operation and economic efficiency of marine reefer containers.