DC-Plasma arc behavior is one of the key factors on growth of diamond film. The results show that keeping steady DC-Plasma arc can grow better quality diamond film. In a long-time growth of diamond film, there is sediment carbon on about 5mm border-entad anode annulus, which was proved to be graphite. It results in fluctuating and instability of DC-Plasma arc and in the DC-Plasma density, which causes graphite generation and much stress in the film. By means of adjusting anode annulus assembly, pausing the supply of carbon source and increasing H2, the problem of sediment carbon cab be effectively resolved. Finally, the mechanism of the effect of arc behavior on growth of diamond film is discussed.