The invention relates to a ramjet combustion chamber, and provides a ramjet combustion chamber stabilizer and a flame stabilization method. The problems that existing mechanical flame stabilizers havelarge pneumatic loss and narrow flame stabilization range, and consequently the working reliability is low, and the requirement of efficient flame stabilization under the high Mach number cannot be met are solved. The ramjet combustion chamber stabilizer includes a sweepback arc-shaped supporting plate, the sweepback arc-shaped supporting plate includes a bottom face, two end faces and two side profiles, the cross section of the sweepback arc-shaped supporting plate is triangle-like, the front parts of the two side profiles are connected, and the two side profiles are concaved to form an arcside profile.