Rational design of photocatalysts to enhance the photocatalytic non-oxidative coupling of methane (NOCM) activity remains a great challenge. Herein, a composite photocatalyst Au/ZnGa2O4/ZnO (Au/ZGO/ZnO) with tandem heterojunctions was prepared by a hydrothermal method and impregnation reduction method for the photocatalytic NOCM reaction. The tandem heterojunctions effectively promote the migration of photogenerated electrons of ZGO and ZnO through the ZGO/ZnO S-scheme heterojunction and the Au/ZnO Schottky junction to Au active sites, significantly enhancing the photocatalytic NOCM activity. The C2H6 and H2 yields of the optimized photocatalyst Au0.75/ZGO/ZnO-15 are 12.2 and 10.3 μmol·g-1, with a ratio close to 1:1, within 4hours under simulated solar light irradiation. The C2H6 production of Au0.75/ZGO/ZnO-15 is 4.5 and 21.4 times higher than that of Au0.75/ZnO and Au0.75/ZGO, respectively. This work provides a strategy for enhancing the photocatalytic NOCM of semiconductor photocatalysts and marks an important step toward the design and synthesis of dual-heterostructures composite photocatalysts.