A new ignition method is proposed called flame accelerated ignition, which is realized by a flame acceleration tunnel set between the spark plug and the main chamber with annular spoilers inside. The investigation of flame accelerated ignition was experimentally accomplished on both a rapid compression machine with optical accessibility and a single-cylinder heavy duty engine. In rapid compression machine study, synchronous pressure sensing and high-speed photography were used with spark ignition cases tested for comparison. The results show that the combustion process is significantly accelerated by flame acceleration ignition. The combustion duration is shortened by more than 30% under all loads compared with spark ignition. According to the optical results, the axial speed of flame outside the flame acceleration tunnel reaches at least 30 m/s and shows positive correlation with load, which is over 10 times than that of conventional flame propagation caused by spark ignition. As a result, a cylindrical flame column is generated in the main chamber soon after the spark plug discharged at the top end of flame acceleration tunnel, inducing the following combustion process completed rapidly. The results from rapid compression machine experiments indicate the potential to increase thermal efficiency by flame accelerated ignition due to the reduced combustion duration, which show great capacity to cut down the negative work with the constant volume degree increased. Experiments were conducted in a single-cylinder heavy duty engine to verify the efficiency potential. Compared with conventional spark ignition, same combustion phase is realized with retarded ignition timing. Meanwhile the heat release is more concentrated. As a result, more efficiency is gained in comparison of the conventional one.