For the vertical vibration of cold rolling mill, a simplified model on vertical vibration of mill was established based on the analysis of cold rolling mill vibration mechanism, and influences of reduction, roll gap friction coefficient and damping on the vertical vibration of rolling mill were analyzed by numerical simulation method. The results show that to decrease the reduction rate can improve the vibration critical speed, to increase the roll gap fiction coefficient can reduce vibration displacement, and to increase roll gap damping can effectively reduce vibration amplitude. Furthermore, methods of suppressing the vertical vibration of the cold rolling mill are proposed as follows based on the above conclusions: the critical rolling speed increases from 1340 m·min-1 to 1520 m·min-1 by optimizing each pass reduction; the roll gap friction coefficient increases by reducing the emulsion concentration properly, and channeling phenomena should be considered in the adjustment process; the roll gap damping increases by adding hydraulic liner shock absorber or porous damper shock absorbers.