Abstract: Electromagnetic (EM) wave propagation in maritime atmospheric duct environments exhibits long-range and low-loss characteristics, while simultaneously posing significant challenges to radar target detection and imaging. To evaluate the impact of atmospheric ducts on the time-domain scattering characteristics of maritime targets, this paper proposes a time-domain hybrid simulation method that combines the three-dimensional parabolic equation method (3DPE) with the physical optics method (PO). The proposed approach leverages the advantages of the 3DPE in modeling EM wave propagation in atmospheric ducts, while efficiently incorporating the PO to model the scattering characteristics of the target, thereby enabling effective simulation of EM scattering in oceanic environments. Based on this framework, phase compensation and Fourier synthesis techniques are introduced, and the transient scattering echo at the receiver is obtained through intra-band multi-frequency point scanning. A comparative analysis with the conventional PO is conducted to demonstrate the feasibility and accuracy of the proposed approach. Furthermore, by establishing typical maritime atmospheric duct scenarios, the high-range resolution profile (HRRP) of ship targets under different ducting conditions are simulated and analyzed. The results show that the HRRP characteristics of maritime targets are not only closely related to the distribution of strong scattering points on the target itself but are also significantly influenced by the propagation characteristics of the atmospheric duct. The findings provide theoretical reference and engineering guidance for the design and application of long-range detection systems over the ocean.