Plenty of heat is generated in rail milling-grinding operation which will cause continuous heat rise around the work-piece area, excessive heat can affect the milling-grinding quality. Based on linear heat source method, the temperature field model of form milling and form grinding was built respectively and the joint milling-grinding temperature model was deduced via the superposition of temperature field. The temperature changing curves on the work-piece surface were attained by MATLAB simulation. The milling-grinding experiments were conducted on the specially-built platform which includes cutting and measuring system to obtain the temperature changing curves, and the results were compared with simulation ones to demonstrate the validity of the model. The model can predict the milling-grinding temperature and the temperature control is realized by milling-grinding speed ratio and selecting processing parameters to prevent the rail material burns.