Abstract: In order to research and develop compact radio frequency(RF)-excited waveguide laser and study the factors affecting laser output performance, a compact RF-excited rectangle waveguide CO₂ laser was designed and developed by using parallel plane resonator and inner electrode structure. Output mirror of transmissivity 20% was used in the experiment. Under the gas pressure of 14kPa, laser power is up to 12W and the optimal electron-photon conversion efficiency reaches 9.4%. The results show that gas pressure and input power are the main factors affecting laser output performance. The experimental results achieve the expected experimental results and provide technical references for the development of this type of appliance.