The invention discloses a technical field related to liquid rocket engines of aerospace propulsion systems, specifically a nitrous oxide and propane rocket engine torch ignition device, which is composed of nitrous oxide electromagnetic valve seats, igniter seats, and nitrous oxide catalytic decomposition Chamber, propane solenoid valve seat, outer core body, inner core body, flow stabilizer, propane liquid collection chamber, upstream propane injection hole, downstream propane injection hole, nitrous oxide liquid collection chamber, nitrous oxide injection Orifice, torch combustion chamber, nitrous oxide inlet, and propane inlet. The decomposition product of the catalytic decomposition chamber forms a primary torch with upstream propane, and the nitrous oxide from the radial injection hole forms a secondary torch with downstream propane, which is used for The rocket motor ignites and starts. The invention can obtain a stable and high-energy ignition torch, and can realize reliable ignition and start of a rocket engine combined with nitrous oxide and propane propellant.