Pulsed power loads (PPLs) are expected to be more widely used in aircraft, warships, and satellites. However, the highly pulsed and periodic characteristics of the PPLs make these DC microgrids’ bus voltage more vulnerable to instability. The small-signal model-based stability analysis approaches are inaccurate due to the large power disturbances caused by the PPLs. On the other hand, the question of what kind of the PPLs can be well handled by an existing DC power distribution system becomes an interest for the power system engineers and researchers. To address the issue, this paper investigates why PPLs have the pulsed power behavior. Then, the large-signal-based Hamiltonian surface shaping power flow (HSSPF) theory is adopted to estimate the stable operation region (SOR) of a cascaded DC power distribution system with PPLs. Moreover, a time-domain bus voltage standard, along with the HSSPF stability criteria, is employed for the stability analysis. Simulations of a DC power distribution system with two typical PPLs are conducted to verify the effectiveness of SOR.