Thermal analysis instruments usually have high performance requirements, and the study of the temperature field distribution of the furnace is the prerequisite for the realization of precise econometric analysis.Due to the influence of air flow on the temperature distribution, the traditional furnace is prone to measurement error. Adjustingthe mechanical structure of furnace can improve the accuracy of the equipmentand change its temperature drift characteristics.In this paper, a threedimensional optimal distribution model of furnace body is established.And the finite element analysis software is used to analyze the temperature field.In this paper, with the analysis of thermodynamics, heat transfer methods, temperature field distribution under different inlet flow, the relationship between the temperature field distribution of the furnace and the gas flow, and the direction of the furnace is described.It provides a theoretical basis for improving the accuracy of temperature control of the thermal analysis instrument.The analysis method and theoretical results can be used as a reference for distribution of thermal analysis instrument furnace temperature field and uniform temperature region in the furnace. And then it provides the basis for the research of the temperature control of the thermal analyzer. And it can lay a foundation for improving the repeat ability, accuracy and stability of the thermal analysis instrument.