The distribution of niobium on the vertical section of casting of GH169 superalloy pneumatic plate wheel was studied by original position statistic distribution analysis technique in the present paper. On the basis of analysis to ten thousands of primary signals at the corresponding original positions of the sample systematically, the quantitative statistic distribution information was obtained. The biggest segregation degrees of niobium in different areas of pneumatic plate wheel vertical section were calculated accurately. Two new models — the total weight ratio of niobium contents within the permissive content range (C₀±R) and the confidence extension ratio of median value (K) at 95 % of confidence limit of weight ratio, were also presented. All these above methods have been used to determine the homogeneity and statistic fitting degree of niobium in the vertical section of casting of GH169 superalloy pneumatic plate wheel accurately for quality control.