Abstract:According to the requirements of current regulations and specifications, for the grade Ⅱ standard platinum resistance thermometer in the range of (- 189.3442 ~ 419.527) ℃, the influencing factors and uncertainty components of resistance value at each temperature point are analyzed and evaluated, and the combined uncertainty and expanded uncertainty of measured parameters Rtp, WZn, WSn, WHg and WAr are calculated, In the evaluation, considering the correlation influence of electrical measuring equipment on resistance ratio W, it is also found that there are unreasonable provisions on the metrological characteristics of fixed point devices in the current specifications.