Abstract: The actuator-lag-volume"is adopted as a physical model for stage of compressor instead of "actuator-lumped volume" model used by other authors in recent years. For comparison the stall lines of a multi-stage axial flow com-pressor have been predicted with these two models respectively . In addition to comparing the simulation with experimental results of compressor rig, the experiments on forcing the engine into stall have been conducted to verify the simulation. It is obvious that the stall line obtained from the new model is in better agreement with the stall points from engine test,but the stall line predicted with the old model is located at the right side below the stall line of compressor rig. The appearence of unstability prior to the real stall points can be also found in the simulation results of other authors. This shows that the new model improves the simulation.When simulating the stability,the stage's mutual matching under off-design conditions is also in good agreement with experimental lines.