Developing new high-entropy alloy system has been a subject of significant research interest in recent years. However, it is a challenge to enhance the impact-resistance property in existing high-entropy alloys. Here we proposed a combination strategy of strengthening via second phase and grain refining to build a network microstructure in Co2Ni2CrVTa0.3 high entropy alloys that could significantly enhance the ballistic limit velocity from 407.8 m/s to 435.4 m/s. Especially, under a high impact velocity of 750 m/s, the energy absorption of the alloy was evidently larger than that of the Ta-free alloy. The microstructure of Co2Ni2CrVTax alloys could be sensitively tuned via Ta addition because of the Ta-induced multi-scale microstructure involving the micro-scale Laves phase and nano-scale L12 structure precipitates. This should be the structural mechanism of the enhanced impact-resistance property, and will shed light on the development of alloys with excellent impact-resistance property.