An axially extracted virtual cathode oscillator(vircator) with a feedbackannulus is configured through particle-in-cell(PIC) simulation. And the effects of thefeedbackmechanism are studied through PIC method. The simulationresults indicate that the new vircator can increase the output power more than two times compared with the conventionalaxiallyextracted vircator under the same condition. Besides it can narrow the bandwidth and purify the modes.