Metal-Organic Frameworks (MOFs) possess a high specific surface area, adjustable pore structures, and abundant active sites. These characteristics demonstrate their unique potential in the field of viscosity reduction of heavy oil. This article systematically reviews the research progress of MOFs used in the field of heavy oil viscosity reduction. Firstly, the types and structural characteristics of MOFs, as well as the mechanism of heavy oil viscosity, are introduced. Then, by analyzing the structural characteristics of MOFs and the structure-activity relationship between heavy oil components, the synergistic mechanism of MOFs in physical adsorption, catalytic cracking, and interface regulation is revealed. The mechanism of MOFs viscosity reduction is discussed in detail. Finally, prospects for the industrial application of MOFs are proposed, providing new ideas for the green development of oil fields under the "dual carbon" goal.