The effects of turbulence on the flame propagation in the propane-air mixture in a closed vessel were investigated by analyzing the high speed motion pictures of flame, the ion-currents due to combustion and the change of the gas compositions in combustion zone. In the combustion chamber, the uniform turbulent conditions were produced by moving suddenly a perforated plate which was driven by the spring and the electro-magnetic control system. The main results are as follows: (1) The combustion zone of turbulent flame may be composed of a lot of flame elements which are similar to laminar flame, and the apparent burning velocity is increased by enlargement of combustion zone due to turbulence. (2) during the early stage following ignition, the flame speed is affected by both factors of mixture strength and intensity of turbulence. with further development of the flame, however, the intensity of turbulence becomes a dominant factor determining thee flame speed.