A 2B 2O 7 system compounds, which usually present three phase structures mainly based on the ionic radius ratios of r A and r B ( r A/ r B), have been studied for potential applications in many fields, such as thermal barrier coatings, luminescence powders, fast-ion conductors, photocatalysts, and matrices for immobilization of highly active radionuclides. Since 2005, La 2Hf 2O 7 was fabricated into transparent ceramics and much more attentions were paid on A 2B 2O 7 transparent ceramics for new applications. In this review, the development of A 2B 2O 7 system transparent ceramics was described. The structure characteristics, powder synthesis method, and sintering techniques of the final A 2B 2O 7 transparent ceramics were summarized. After that, the mostly reported A 2Hf 2O 7, A 2Zr 2O 7, and A 2Ti 2O 7 system transparent ceramics were systematically introduced. The potential application fields and future development trends were also discussed, focusing on scintillators, optical elements, and other luminescent materials.