The adaptive cycle engine can maintain good performance in both supersonic and subsonic cruise with a wide adjustment range of bypass ratio. In this paper, the performance model of the adaptive cycle engine was established, using the XA100 as a baseline engine. Based on the performance model, the mass flow rate. The effect of mass flow distribution between the first and second splitters on the specific thrust and specific fuel consumption was analyzed. The results show that under the same bypass ratio, the first split ratio has a more effect on specific thrust than the second split ratio. The first split ratio reduced from 0.6 to 0.1, specific thrust increases by 24.3%. And the second split ratio has a greater effect on specific fuel consumption. The second split ratio increased from 0.1 to 0.5, saving 11.1% on specific fuel consumption. Then, the experimental model of the multistage splitter system (first and second splitters) and FVABI of the ACE was completed. And the experimental results show that the performance of the first and second splitters remain above 0.965 under the different mass-flow-ratio combinations. At the same time, the airflow of the CDFS duct has a stronger adjusting effect on the airflow of the second splitter than that of the first splitter.