According to heat-conduction theory and face-gear meshing characteristics, transient thermal analysis is conducted with APDL language for moving heat source loading , the node temperature data in different regions of face-gear tooth surface is obtained under different working conditions. Results indicate that during face gear transmisson, improving face-gear tooth surface precision, using lubricating oil with relative high dynamic viscosity and lowering face-gear rotate speed and contact load could help to prolong face-gear service life. The conclusions provide temperature data of tooth surface meshing for face-gear life prediction.