Abstract: Single-atom catalysts (SACs) have unique advantages in the field of catalytic water electrolysis due to their advantages of high atomic utilization, clear active center, high specific activity and stability, and metal-support interaction in materials can have a significant impact on the catalytic process. In this paper, the characteristics of single-atom catalysts and their unique advantages in studying the structure and structure-activity relationship of electrocatalytic electrocatalysts are first clarified. Secondly, the important role of oxide support in stabilizing and dispersing active species, adsorbing and activating reactants, regulating central electronic structure and directly participating in chemical reactions of single-atom catalysts is reviewed, and how the support achieves these functions through structural defects, surface groups, spatial confinement and lattice interaction is analyzed in detail. Then, the differences in coordination binding of single atoms on different carriers and the performance of hydrogen evolution and oxygen evolution reactions are compared with examples. Finally, we present our insights into the opportunities and challenges, key problems and possible solutions of how to modulate catalyst performance through the interaction of support and single atoms.