We have successfully developed a system for deposition of large area diamond films by a DC arc plasma jet operated in gas recycling mode. In the present paper, the influence of substrate temperature, methane concentration, flow rate of feeding gas and the input power of the jet for diamond film deposition is presented. Deposition of a large area of uniform thickness high quality diamond wafer of Φ65 mm in diameter at a growth rate of 15 μm/h is reported. The thickness of the wafer is 0.7 mm and the thermal conductivity can be 18.1 W/cm K
