A novel carbon dioxide fixation pathway, 3-hydroxypropionate cycle, has been discovered in thermophilic filamentous photosynthetic bacteria such as Chloroflexus aurantiacus, which can grow in several conditions. The characteristic of this pathway is 3-hydroxypropionate as a metabolic intermediate, which can be used for synthesis of many valuable products in industry. In this minireview, the discovery of this unique biosynthetic process, the development of the reaction mechanism and the latest progress are introduced, especially the involvement of several multifunction enzymes. Besides theoretical significance, potential biotechnological applications of the 3-hydroxypropionate pathway are also discussed.