The invention discloses a scramjet engine capable of promoting supersonic combustion performance of a boron-based fuel-rich solid propellant. The scramjet engine is installed at the lower part of an aircraft main body, and comprises an engine main body and fuel gas generators; the interior of the aircraft main body is provided with a loading space; the fuel gas generators are arranged in the loading space; the engine main body comprises an intake passage, an isolation section, a supersonic combustor and an exhaust nozzle which communicate in sequence from the front to the rear; the fuel gas generators are an inflammable propellant fuel gas generator and a fuel-rich solid propellant fuel gas generator which are independent from each other; the inflammable propellant fuel gas generator and the fuel-rich solid propellant fuel gas generator are each connected with a nozzle tube and a diversion tube; and an airflow outlet of each diversion tube faces towards the interior of the supersonic combustor. The scramjet engine is capable of obviously promoting the combustion performance of the boron-based fuel-rich solid propellant under a supersonic inflow condition in a relatively short time,and the problems that the research difficulty and the research period of formula development and technical preparation of the propellant are respectively high and long, and the like can be avoided temporarily, so that the scramjet engine is high in practicability.