This paper ains to systematically study the effects of discharge parameters on plasma in a 5 kW cylindrical single- mode microwave plasma chemical vapor deposition device. The relationship between the motion and distribution of microwave plasma and the discharge parameters was analyzed by means of simulation and experimental control. The plasma environment was diagnosed by way of the emission spectrum. Meanwhile, the morphology and quality of the diamond film deposited were characterized by SEM and Raman, so as to verify the regulation principle of MPCVD device. The experimental results showed