Photocatalytic reduction of CO2 with H2O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry. Nevertheless, the precise control of CO/H2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further appli-cation. Herein, we prepared a series of highly efficient heterostructure based on highly dispersed palla-dium supported on ultrathin CoAl-layered double hydroxide (LDH). In conjunction with a Ru-complex sensitizer, the molar ratios of CO/H2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation (λ >400 nm). More interestingly, the syngas can be obtained under light irradiation atλ >600 nm. Struc-ture characterization and density functional theory calculations revealed that the remarkable catalytic ac-tivity can be due to the supported palladium, which improved the charge transfer efficiency. Meanwhile, more H atoms were used to generate H2 on the supported palladium for further tunable CO/H2 ratio. This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock.