In the study of indirectly driven laser fusion, the flat response X-ray diode is the main detector for the measurement of X-ray radiation energy flux. To obtain ideal flat response effect, it usually costs a lot of time to optimize the composite filter parameters of the detector. In this paper, the particle swarm optimization algorithm is developed and applied to optimize the parameters of compound filter of flat response X-ray diode. Compared with the previous work, the method developed in this paper can get the optimized parameters of composite filter more quickly and accurately. On this basis, this paper proposes a new filter combination mode, optimizes its flat response characteristics, and obtains a better parameter ratio than the traditional filter combination. The work in this paper provides a more efficient method for searching the parameters of the composite filter of the response X-ray diode