Abstract: Laser plasma ignition(LPI) is viewed as a promising ignition technique for aerospace propulsion systems with its many merits over conventional ignition techniques, including easier control of the ignition position and timing, wider working condition, less electromagnetic interference, rapid response and feasibility of reliable r-ignitions, etc.. Firstly, an introduction to the technical benefits and physical processes of the LPI technique was given. Then the developments in the applications of the LPI in aerospace propulsion systems were summarized, especially the achievements that had been made in National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology. Finally, the challenges and prospects in the application of the LPI in aerospace propulsion systems were analyzed. The LPI has demonstrated great prospects in reliable r-ignition of the rocket engines fueled with no-toxic no-hypergolic propellants and scramjet engines fueled with hydrocarbon fuels. However, to facilitate the in orbit and on board applications, further progress should be made in the integrated system design of the LPI system with the propulsion systems, and in the miniaturization and engineering design of the LPI system.