Abstract: Microstructure of diamond films deposited by combustion flame (CFD) in the air was analyzed by transmission electron microscopy(TEM). The result showed that there are stacking faults and microtwins in diamond crystalline, which dominatly exist on 111 planes. Dislocations are also found in the diamond crystalline. There was higher dislocations density in middle of diamond crystalline than that in baundary. Finally the non-diamond type carbon impurities was found between the diamond grains in the diamond film, which are amorphous carbon and/or microcrystalline graphite.