The invention provides a space propulsion method of a
nanosecond-
femtosecond composite light filament, which is used for solving the problem of low long-distance
laser propulsion efficiency. The method specifically comprises the following steps: forming a kilometer-level length filament through a space filament forming principle of
femtosecond laser, stabilizing the
power density at 1013-1015W / cm < 2 > magnitude by utilizing a
light intensity clamping effect, and realizing dozens of kilometer-level low-loss energy transmission; meanwhile, the transmission direction of the
nanosecond laser is adjusted through the optical lens group, the formed
nanosecond filament and the
femtosecond laser are coaxially transmitted or transmitted at a certain angle and act on the same position, a
plasma channel generated by the filament enables the
transmission loss of the high-energy
nanosecond laser to be greatly reduced, and the
energy absorption of the target material to the
nanosecond laser is remarkably improved; therefore, the surface of the target material is melted, gasified and even ionized in an extremely short time, a large number of high-speed reverse-spraying
plasma plumes are generated, and high
specific impulse and thrust are obtained. The method is suitable for various target materials, and precise control over the thrust, the
specific impulse and the propelling direction can be achieved by regulating and controlling laser parameters.