Key technologies in Maglev launch assist for space launch were studied, such as magnetic levitation (Maglev), linear motor acceleration, aerodynamic effect and space vehicle separating technology. By the comparison of several Maglev systems, high temperature superconductor (HTS) electrodynamic suspension (EDS) system was viewed as a suited one for Maglev launch assist. Based on the static and dynamic experiments of a HTS unit, the levitation and guidance force, rigidity and damping characteristics of the HTS Maglev system were indicated. Then a demo Maglev launch assist test vehicle was built to estimate its levitation performance. By analyzing the advantage and disadvantage of two kinds of linear motor, the double-side inductive linear motor was considered a suited one, and the pulsed MHD generator was the feasible power supply system for the linear motor acceleration. Aerodynamic effect on the Maglev vehicle was studied, and the aerodynamic shape and layout were designed optimally. The basic aerodynamics characteristics were concluded, and the aerodynamic aerofoil was useful for balancing the pitching moment of the Maglev vehicle. The technology of space vehicle separating simultaneously from the direction guideway on the Maglev vehicle was studied. Based on the D' Alan Bert theory, the primary kinetic parameters of space vehicle slipping successfully away from the Maglev vehicle were obtained.