In order to solve the problem of low cost-benefit ratio in the attack of low-speed small UAVs and their swarms, an attack scheme based on 60 mm mortar directed fragment mortar was proposed. Autodyn software is used to simulate the static explosion state of the aimed warhead, and the vulnerability model of the UAV is established according to the structural characteristics of the typical target UAV; Based on the coordinate damage law, the damage probability calculation model is established to determine the number of effective fragments hitting the target under multiple working conditions, the damage probability of different levels of UAV targets, and the damage effect of UAV groups on multiple targets under different arrangements. The results show that the scheme can cause effective damage to "low, slow and small" UAV and swarm under the condition of fixed distance fuze.