Abstract: According to the machining technology of the five-axis machining center on titanium alloy materials, associating with the characteristics of machining and the applying condition, confirming the technical parameters of the high torque bi-rotary structure, accomplishing the design of the milling head entirely. Basing on FEM optimization and analysis calculation, providing theoretical basis and references to the high torque bi-rotary milling head on designing, amelioration and manufacturing, satisfying the requirements of the milling head with high efficiency, high precision and high stability.