According to the structure characteristics of herringbone gear transmission, the dynamic response of the gear box is researched in consideration of the excitation (such as: time-varying mesh stiffness, gear errors and inertial force), herringbone gears axial positioning and sliding bearing. The model is solved by using the Newmark integrals method, then the time history of system dynamic force is obtained. Taking bearing force as excitations the gearbox noise radiation characteristics are researched. The distribution of sound pressure and frequency spectrum for noise of the field points are obtained, then the spatial distribution and frequency components of the noise are analyzed. The effects of the connection stiffness of left and right sides of herringbone gears and axial support stiffness on the noise radiation characteristics are discussed. The study provides useful theoretical guideline to the design of the gear box.