This paper mainly conducts experimental and numerical simulation studies on the combustion characteristics of H2/landfill gas laminar premixed flames. The laminar burning velocity of CH4/CO2/H2 mixtures is measured with a fixed-volume combustion bomb. The study results indicate the mixture's laminar burning velocity approximately grows linearly with the H2 content, and the rate of increase also rises with the increase of equivalence ratio. The variation trend of the adiabatic flame temperature with equivalence ratio is similar to that of laminar burning velocity. Compared to the thermal diffusivity, The adiabatic flame temperature has a greater effect on laminar burning velocity. Under lean combustion conditions, as the H2 content increases, the thermal diffusion instability gradually intensifies, while it is the opposite under rich combustion conditions. The hydrodynamic instability gradually intensifies with the increase of H2 content, while first intensifies and then weakens with the increase of equivalence ratio. The increase in H2 content enhances the laminar burning velocity by increasing the mole fraction of relevant free radicals and the reaction rate of the main reaction. The maximum mole fraction of NO gradually increases with the rise of the H2 content for different equivalence ratios. The increase in H2 content strengthens the contribution of thermal mechanism reactions in NO formation.