Abstract: This paper proposes a depth estimation method for multi-highlight targets in deep-sea active sonar systems based on multipath time-delay response matching. The study develops a two-way acoustic ray propagation model for acitive sonar. The model analyzes the depth-dependent characteristics of relative time delays between direct and surface-reflected waves. Based on this analysis, a frequency-domain matching model was developed to achieve depth estimation of active targets. Theoretical analysis confirmed the effectiveness of this depth estimation method for multi-highlight targets. Numerical simulations and error analysis confirm the stability and effectiveness of the algorithm. The sea trial shows successful depth estimation for a target at 18 km with errors within 5 m.