The imaging of underwater objects illuminated by artificial light has been of long-standing interest to investigators working in oceanographic environments. Pulsed lasers together with range-gated technology have been widely used for underwater optical imaging applications. In order to describe the formation of underwater range-gated images, a pulsed laser underwater imaging model based on pulse spatial and temporal broadening is proposed. Experiments based on a self-assembled laser range-gated imaging system were implemented in our laboratory. Results show good agreements between experiments and simulations. Both results also confirm higher image contrast toward the tail region of the target-reflected light. Furthermore, experiments on underwater image blur and restoration are also implemented and show good image recovery results. The modulation transfer function-based restoration mechanism also implies a way to eliminate the blur effect caused by light forward scattering.