Abstract: The high speed Schlieren photography system and pressure sensors were used to investigate the flame propagation process of methane-air mixture in a small horizontal tube. The flame structure, propagation velocity and mixture pressure were obtained from the experiment. The results show that flame structure changes greatly in the flame propagation process, suddenly changing from a spherical laminar flame pointing forward to a V shape turbulent flame forming a cusp toward the burned gas. In this process, the velocity decreases but the pressure increases continuously. With the k-ε turbulent combustion model, unsteady premixed methane flame in a 2D matrix burner was numerically simulated. The characteristics of flame propagation and flame structure variation qualitatively agree with the experimental data very well.