Heterostructures (HSs) have attracted significant attention because of their interlayer van der Waals interactions.The electronic structures and optical properties of stacked GaN-MoS2 HSs under strain have been explored in this work using density functional theory.The results indicate that the direct band gap (1.95 eV) of the GaN-MoS2 HS is lower than the individual band gaps of both the GaN layer (3.48 eV) and the MoS2 layer (2.03 eV) based on HSE06 hybrid functional calculations.Specifically,the GaN-MoS2 HS is a typical type-Ⅱ band HS semiconductor that provides an effective approach to enhance the charge separation efficiency for improved photocatalytic degradation activity and water splitting efficiency.Under tensile or compressive strain,the direct band gap of the GaN-MoS2 HS undergoes redshifts.Additionally,the GaNMoS2 HS maintains its direct band gap semiconductor behavior even when the tensile or compressive strain reaches 5％ or -5％.Therefore,the results reported above can be used to expand the application of GaN-MoS2 HSs to photovoltaic cells and photocatalysts.