Continuous-wave LDV (laser Doppler velocimeters) are limited in low-altitude velocity measurement due to factors such as the low power of continuous-wave lasers and optical system diffraction. By introducing the concept of "virtual distance" to expand the Feuilleté model, the time-domain echo signal model for pulsed LDV had been established. Simulation results indicate that pulsed LDV can perform velocity measurement through the accumulation of hard target echo signals. Pulsed LDV can also utilize longer laser pulse widths for detection without restricted by spatial resolution, the feasibility of high-precision velocity measurement using long pulses with pulsed LDV is verifies, laying a theoretical foundation for future experimental validation of the pulsed LDV. Pulsed LDV is capable of detecting echo signals scattered from targets at 5 km and beyond, significantly extending the working distance range of LDV. This makes LDV applicable in integrated navigation of low-altitude aircrafts and planetary surface landing navigation for spacecrafts, and other scenarios that require long-distance high-precision velocity measurement.