Cutting force, temperature, and stress on a cutting tool reflect the working condition of the cutting tool. Among these, the cutting force is relatively easier to be monitored and more reflective of the machining process stability. In this study, a new model of the milling force applied for a complex profile milling cutter has been developed based on the infinitesimal method. A dynamic contact model has been implemented through analyzing the working status of each section on the complex milling cutter. An underlying database is established in the form of response surfaces from simulation. The model of milling force for a complex profile milling cutter has been validated to be accurate by the comparison between the calculated and measured milling forces.