A stabilizer that maintains a steady propellant mixture ratio in a liquid bipropellant rocket engine was introduced. First, a design criterion for the ideal performance of a general stabilizer was derived. A new stabilizer with bellows (bellows-type stabilizer) was proposed in the present study and relevant design parameters were identified by a mathematical model as well as a theoretical analysis. Governing equations were established to predict the static behaviour of the stabilizer. A bellows-type stabilizer was fabricated and its performance was measured. The performance predicted by the mathematical model showed satisfactory agreement with measurements and this validates the adequacy of the mathematical model proposed in the present study.