Abstract: Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating foliar disease of wheat. The identification and utilization of elite resistant germplasm is an effective control measure of the disease. At present, most wheat cultivars/lines in China's wheat production are susceptible to powdery mildew. Moreover, few powdery mildew resistance genes are used in China. Therefore, it is essential to identify more effective and elite resistance sources and genes. The 'Hongyouzi' Chinese wheat landrace ('Jing 2350') has shown immune to high resistant of 34 out of 38 Bgt isolates at seedling stage and immune or nearly immune in the field to a composites of Bgt isolates at mature stage in Shijiazhuang, China. To further study the resistance feature and identify the resistance gene (s) of 'Hongyouzi', genetic analysis of F₁ plants, F₂ populations and their derived F_2:3 families respectively from crosses of 'Huixianhong'×'Hongyouzi' and 'Hongyouzi'×'Mingxian169' were conducted at seedling stage. The results showed that all F₁ plants derived from the combinations of 'Huixianhong'×'Hongyouzi' and 'Hongyouzi'×'Mingxian169' were susceptible to Bgt isolate E09. The ratios of resistant F₂ plants to susceptible plants conformed as 1︰3 and those of homozygous resistant F_2:3 lines︰heterozygous lines︰homozygous susceptible lines conformed as 1︰2︰1. These results indicated that the resistance of 'Hongyouzi' to Bgt isolate E09 was conferred by a single recessive resistance gene, temporarily named PmHYZ. 'Hongyouzi' was the elite powdery mildew resistance sources of Chinese wheat landraces, thus it was useful to effectively use elite resistance source and resistance gene in breeding resistant crops.