<p>Contact problem of herringbone gears is complex due to the sensitivity to the inevitable manufacturing errors and elasticity deformation. A new semi-analytical slice (SAS) model of herringbone gears is developed in this paper for analyzing the elastic contact behavior with errors. The geometry model of herringbone gears is established, in which the herringbone gears are discretized into slices and errors are explicitly depicted. The elasticity of herringbone gears is efficiently and accurately addressed by the semi-analytical method combining the advantage of analytical method and finite element (FE) method. Based on the geometry and elasticity modeling, the SAS model of herringbone gears is developed by the derivation of compatibility and equilibrium equations. Upon the model, the mesh stiffness, transmission error (TE) and load distribution behavior of herringbone gears considering the elasticity and errors are analyzed. The effectiveness of the SAS model is verified by the FE model in ANSYS software. It is expected that the proposed SAS model is significant to the analysis and optimization for the herringbone gear transmission.</p>