Abstract: The frequency, quality factor and gap impedance of outloaded resonant cavity have been calculated analytically by the equivalent circuit model, and the results agree well with those of electromagnetic simulation software. The analytical and simulated results show that the main cavity’s quality factor can be depressed through the outload technology and the bandwidth can be extended with the mode overlapping. In addition, with the equivalent circuit model, the influences of the main and absorbing cavities’quality factors, the frequency deviation between the main and absorbing cavities, and the coupling parameters on the quality factors as well as gap impedance of the outloaded resonant cavity have been considered．