［Objective］This study investigated the influence of different soft segment types（PPG， PCL，PTMG）on the impact resistance of polyurea，aiming to provide a theoretical basis for designinghigh-performance protective coatings and their engineering applications.［Methods］ Three spraypolyureas with different soft segment structures were synthesized via the prepolymer method. Theirchemical structures，thermal properties，dynamic mechanical behavior，energy dissipation capacity，and impact resistance were systematically characterized using Fourier transform infrared spectroscopy（FT-IR）， differential scanning calorimetry（DSC）， cyclic tensile testing，and drop-weight impact experiments.［Results］The soft segment structure significantly affected the microphase separation andmechanical properties of spray polyurea. PTMG-based spray polyurea exhibited the most pronouncedmicrophase separation，along with the highest tensile strength（28 MPa） and fracture energy（1 078. 55 kJ/m²）. However，its tendency toward brittle fracture in thick coatings（2 mm） could exacerbate substrate damage. In contrast，PCL-based spray polyurea achieved an optimal balance between strength，modulus and toughness. Under thick coating conditions，it effectively absorbed impact energy through large deformation，demonstrating superior impact protection performance. PPG-based spray polyurea was the most flexible（with the lowest T_g）. Its protective effectiveness relied on sufficiently thick coatings（≥1. 5 mm）to facilitate energy dissipation. All spray polyureas tested showed significant strain rate sensitivity，with both modulus and strength increasing with higher loading rates.［Conclusion］The impact resistance of spray polyurea was determined collectively by the chemical structure of the soft segment（which governed the microphase separation behavior and intrinsic toughness）and the coating thickness（which dictated the volume of energy absorption）. Owing to its superior overall properties，PCL-based spray polyurea represented the optimal choice for thick coatingsunder extreme impact conditions（e. g.，explosions and projectile impacts）. PPG-based spray polyureawas more suitable for vibration damping and shock absorption applications，while PTMG-based spraypolyurea was better adapted for use in thin coatings or scenarios requiring high strength under moderate（non-extreme）impact.