With particle simulation and experiment, an axial feedback vircator is studied in detail. It shows that the axial feedbacked vircator can lock the microwave operation frequency and increase the microwave power effectively. In our model, It is found that the dominant microwave frequency is approximately unchanged at about 3.5GHz or at about 4.8GHz with the cathodeanode gap greater or less than 1.3cm, respectively, with a diode voltage of about 450kV and the beam current of about 22kA. In addition, it is also found that the coupling of the microwave of 3.5GHz with the cavity mode is good. The experimental results confirm the conclusions obtained in simulation.