介绍了应用二元四次最小二乘拟合法实现热电偶热电势－温度的自动转换；该方法同时实现了热电偶的冷端补偿和非线性校正．通过现场实际应用，证明该算法简单、速度快、精确度高，尤其适用于高速、高精度测控系统的数据处理． This paper introduces the application of quadratic quadratic least squares fitting method to realize the thermocouple thermoelectric potential - temperature conversion automatically. The method also realizes the cold junction compensation and nonlinear correction of the thermocouple. The practical application proves that the algorithm is simple, fast and accurate, especially suitable for the data processing of high speed and high precision measurement and control system.