As resource replenishment, airdrop is an important means. Compared with traditional land and water transportation, the airdrop can guarantee security efficiently for the material, and its capacity has an indispensable impact on the formulation of airdrop plans. At present, the capacity theory understanding of airdrop site scene is fairly superficial. Firstly, the operation characteristics of the airdrop site are studied and analyzed, and the definition of the capacity of the airdrop site is proposed in combination with the operation and structural characteristics of the airdrop site scene, Secondly, the possibility of aircraft chasing situation in the operation on airdrop ground is analyzed, and a capacity calculation model of the airdrop ground is established. Finally, taking a certain airdrop site as an example, the theoretical capacity of the airdrop site under this structure is calculated, and the reliability of the theoretical model is verified by Monte Carlo simulation. At the same time, the variation law of airdrop field capacity under condition of the probability change of aircraft at running speed and less than the minimum safety interval is explored. The research content of the paper can supply formulation of airdrop plan with scientific and reliable theory.