For improvement of productivity and cutting tool lift, cutting force in end milling needs to be predicted accurately. In order to analyze cutting force, the cutting dynamics was modelled mathematically by using chip load, cutting geometry, and the relationship between cutting forces and the chip load. Specific cutting force coefficients of the cutting dynamics model were obtained by average cutting forces, tool diameter, cutting speed, fled, axial depth and radial depth of cut. The effects of the cutting conditions on the specific cutting force constants in milling were studied. The model is verified through comparisons of model predicted cutting forces with measured cutting forces obtained from machining experiments.