This review summarizes the preparation methods of MOF-on-MOF materials and their application progress in the field of photocatalysis. It highlights the unique advantages of such materials in photocatalytic applications and discusses their application examples in areas including environmental remediation, energy conversion, photoelectrochemistry, and the development of antibacterial mate-rials. Finally, it outlines the main challenges currently facing MOF-on-MOF photocatalytic systems and provides an outlook on their future research direc-tions in the field of photocatalysis.