Aiming at the problem that the traditional eight-beam ratio amplitude direction-finding system has huge calibration workload and high real-time requirement， this paper proposes a method to calibrate the system using only five angle points per angle interval， and uses field programmable gate array （FPGA） devices to complete the calibration according to the real-time requirement of the direction-finding system. The whole direction-finding system is divided into internal and external channels， and the system correction source is introduced into the internal channel to realize the dynamic correction of the direction-finding channel， reduce the system error and improve the maintainability of the system. Field test shows that the calibration method can reduce the testing workload and the final system direction finding accuracy meets the requirements of engineering application. The root mean square error of all band direction finding is 2.01°， and the real-time requirement can be achieved by using FPGA device.