Based on the constant volume combustion bomb system and high-speed schlieren technology,the laminar flame combustion characteristics of hydrogenethanolair mixed gas were studied with initial temperature of 450 K, initial pressure of 0.2 MPa, hydrogen content of 50%, 70% and 80% and equivalent ratio of 0.7-1.4. The laminar combustion velocity (LBV) and flame instability of hydrogen-doped gas were studied. The results show that increasing the proportion of hydrogen in fuel can increase the LBV of mixed gas. The LBV of premixed gas with three hydrogen contents all reach the peak at the equivalent ratio of 1.3 and then show a downward trend. With the increase of equivalence ratio, Lb gradually decreases and becomes negative when the equivalence ratio is about 1.4. Cracks appear and develop to cell structure on the flame surface, and the flame is unstable.
