Abstract: The chromosome numbers of 4 species of Genus Rhus from Shaanxi Province are reported as follows: 1, R.chinensis 2ⁿ=30+(0-5)B; 2. R.potaninii 2ⁿ=30, it is reported for the first time; 3. R.typhiflua 2ⁿ=30; 4. R.verniciflua 2ⁿ=30, hut one of 65 cultivars is a triploid 2ⁿ=3x=45.R.chinensis and R.potainii are the host plants of gall makers which produce important Chinese medicine called Chinese gall, R.verniciflua is a kind of particular economic tree in China, and R.typhiflua is a kind of quickgrowing garden plant. The results provide the cytological bases for further using and studying these plants.Until 1977 only in 6 species of woody plants were B-chromosomes discovered. In this paper 0—5 B-chromosomes are found in R.chinensis for the first time. This discovery wiill promote the further studying about the origin and distribution of B-chromosome.This paper also provides some cytological information for the classification of Genus Rhus.