Abstract: The model of the bed and foundation transient temperature was established by ANSYS, meanwhile the temperature data of machine tool bed's key points was obtained by the temperature acquisition device. Based on the measured data, the parameters of the finite element model was modified to make the simulated temperature distribution similar to the actual temperature distribution, which ensured the reliability of the simulation results. According to the thermal characteristics of the machine, three methods were offered to reduce the thermal deformation of the bed: changing the material of structural parts, optimizing the structure and adopting heat capacity balance technology. Conclusion can be drawn that, in terms of thermal stability, the artificial granite material has a certain improvement compared with the traditional cast iron material. And the straightness error of the bed caused by thermal deformation could be eliminated by 31.8% when using the artificial granite material.