Semiconductors of Na1−xLaxTa1−xCrxO3 (x=0–1.00) were prepared with conventional solid state reactions method. The crystal structure changed from monoclinic (x≤0.60) to orthorhombic (x≥0.70) with the modulation of chemical composition. H2 generation under visible light irradiation (λ>420 nm) was successfully obtained with the tuning of band structures of Na1−xLaxTa1−xCrxO3. The highest performance for H2 generation (4.5 μmol/h) was observed at x=0.4 with apparent quantum yield of 0.5%. The visible light harvesting as well as the photocatalysis was further discussed based on the electronic structures thereof.