Green hydrogen energy is one of the best alternatives to fossil fuels. Using the advantage of abundant and renewable ethanol resources to produce hydrogen can effectively make up for the current lack of demand for hydrogen energy. Based on constant volume combustor, the flame propagation characteristics of hydrogen-ethanol fuel under different operating conditions were investigated in this study. Including initial temperature 450 K, initial pressure 0.2 MPa, equivalent ratio 0.7–1.4, hydrogen mixing ratio 0%, 40%, 80%. The laminar combustion velocity and Markstein length of mixed gas were calculated, and the influence of tensile ratio on flame propagation velocity was analyzed. The results show that the combustion velocity of the mixed fuel increases with the ratio of hydrogen and equivalent ratio, reaches the maximum value when the equivalent ratio is 1.2, and then begins to decrease. Markstein lengths of all hydrogen-doped ratios decrease with the increase of the equivalent ratio and are positive, indicating that the flame is in a stable state, but the stability of the flame decreases with the increase of the equivalent ratio. By fitting the calculated laminar flow combustion velocity, the empirical formula of laminar flow combustion velocity of ethanol-hydrogen mixed fuel is obtained.