To make research work reproducible and comparable, enhance efficiency, decrease cost, AMESim (Advanced Modeling and Simulation Environment for Systems engineering) is used in studying cutting speed stability of hydraulic milling machines. One simulation model of hydraulic milling machine is established based on AMESim, and cutting rev characteristic of milling machine is studied when the hydraulic system overflow pressure is set different. The results indicate inertia of engine effects milling drum cutting speed stability significantly, and milling drum cutting rev will fluctuate when the maximum output torque is set on a low level, limited by the overflow pressure setting, as milling hydraulic system overflows frequently under the action of alternating load, and ideal overflow pressure setting should insure the relief valve not overflowing all the normal working status.