Abstract: Axial fuel staging（AFS） combustion technology is an advanced low pollution combustion technology for heavy gas engines at present. In order to reveal the effects of H₂/CH₄ fuel species and jet angle on the re-combustion zone flow field and flame structure of axial staged combustion, high-frequency particle image velocimetry（PIV） and OH^*-based self luminescence techniques were used. The effects of 90° and 45° jet angles on the axial staged flow field and the flame structure of different fuels were investigated when the jet equivalence ratio was 0.6 and the momentum flux ratio was 6. Results show that when the jet angle is 90°, there will be an obvious recirculating zone at the root of the jet, and the jet flames have periodic pulsations. When the jet angle is 45°, the shear layer will not produce a significant recirculating zone at the root of the jet, the jet flame burn is more stable, and the chemical residence time of the fuel in the low-speed zone is shorter, which has better adaptability for hydrogen fuel with fast flame propagation speed and easy tempering. The doping of methane fuel with hydrogen increases the propagation speed of the jet flame. With the increase of hydrogen doping ratio, the jet flame gradually changes from a detached flame to a continuous flame, the jet flame branch appears on the windward side, the length of the reaction zone is shortened and smaller, the flame intensity is enhanced, and the flame root moves to the nozzle outlet and finally attaches to the jet nozzle outlet.