As a significant alternative of supersonic ramjet, a kind of solid propellant dual combustor ramjet is investigated in this paper. The performance and characteristic parameters of subsonic duct and supersonic duct effects on the engine overall performance are analyzed through performance calculations and experiment As the calculation results illustrated, the supersonic duct dominates the ramjet performance, while the subsonic duct is more important in ignition and steady combustion. According to the ground experiment, both subsonic and supersonic combustion was stably established, which means this scheme of solid propellant dual combustor ramjet is feasible