Abstract: Rosaceae is a large family of dicotyledoneae and most species in this family are of high economic value. China is one of the most important distribution centers of Rosaceae with more than half total genera in the world. Based on large quantity of reference collection and field investigation to the Tianshan Mountains of China and Kyrgyzstan，using flora comparative methods，flora of Rosaceae in two areas was compared in this study. The results showed that there were significant similarity and difference in the flora between the two areas：（1）there were 24 genera and 85 species in the Tianshan Mountains of China. The component of North Emperate Zone was absolutely dominant in this area（genera 62.50%，species 83.53%）. Flora of these areas also has certain Mediterranean component. The North Temperate Zone and the Mediterranean components are closely related to Old World Temperate and Temperate Asia ones；（2）there were 85 genera and 118 species in the Tianshan Mountains of Kyrgyzstan. The component of North Temperate Zone was also dominantly high percentage（genera 50.00%，species 77.19%）. The component of Old World Temperate and Temperate Asia took high percentage and the species of Old World Temperate were very rich in this area. Old World Temperate and Temperate Asia has a close relation between the species in Mediterranean，east Asia and west Asia and also the component of North Temperate and South Temperate；（3）Quantity of genera and species of Rosaceae in the Tianshan Mountains of Kyrgyzstan were much richer comparing to China，especially being the central Asia mountain species. North Temperate took high percentage in both China and Kyrgyzstan. Similarity coefficients of genera and species in these two areas were 83.02% and 54.90% . Significant difference was found in endemism species that there were 13 endemic species in the Tianshan Mountains of Kyrgyzstan and no endemic species but only 9 endemic variety species in China.

Key words: Rosaceae, the Tianshan Mountains of China and Kyrgyzstan, flora, comparative analysis