Hydrogen is an efficient additive to improve the combustion characteristics of ethanol fuels. For better application in combustion devices, it is necessary to study its laminar combustion characteristics. The experiments are conducted at an initial pressure of 0.1, 0.4 MPa, an initial temperature of 400 K, an equivalent ratio in the range of 0.7~1.4, and the H₂ ratios of 20%, 50% and 80%. The laminar burning velocity (LBV) is obtained using the constant pressure method (CPM). The flame morphology is studied at different stages of flame development, and the flame becomes unstable when the large cracks on the flame surface are split into small cracks and led to the regeneration of new cells. The effects of hydrodynamics and thermal diffusion on the inherent instability of the flame are also investigated. The results show that the LBV increases with the increase of hydrogen proportion, and the enhancement effect is more significant in the hydrogen-rich state. The hydrodynamic instability increases with the increase of pressure, and the thermal diffusion instability is insensitive to the pressure change. In addition, increasing the hydrogen ratio or initial pressure can cause the flame to suffer from instability earlier.