The present invention is a stratospheric-airship-assisted orbital payload launching system that features with high reusability ratio, low cost, short launch-preparation time and robust reliability. The system consists of an airship-based stratospheric launch platform (1), a stratospheric-launched suborbital shuttle (2, SLSS) and an upper stage (3, a modified version of conventional upper stage or a spaceplane). The airship-based stratospheric launch platform (1) employs hydrogen and helium to provide buoyancy in its ascent and high-altitude cruise stages. Given the substantially lower ambient pressure, the usage of hydrogen at high altitude is much safer than on the ground. The SLSS (2) is mounted beneath the platform (1), and an assembly of payload (4) and upper stage (3) is loaded in the cargo bay (2B) of SLSS (2). In a typical orbital payload launching mission, the airship-based stratospheric launch platform (1) ascends to a predetermined altitude in stratosphere, where the air density is much lower than the sea level and wind is relatively slow and steady comparing with the upper troposhere, and then launches the SLSS (2) in a predetermined position and time. After the SLSS (2) is launched, the platform (1) vents hydrogen lifting gas to swiftly unload the extra buoyancy. Subsequently, the platform (1) descends and returns to its ground base. Meanwhile, the SLSS (2) rockets to a predetermined velocity and altitude (above the atmosphere), opens its cargo bay doors (2D) and releases its cargo (i.e., the assembly of upper stage (3) and payload (4)). The upper stage (3) ignites and propels the payload to a predetermined space orbit. At the same time, the SLSS (2) re-enters, and decelerates via aerobraking. It is finally recovered via a conventional wheel landing.