Rosaceae generally exhibit self-incompatibility， which affect both self-compatibility and cross-compatibility. 186 Rosa from the germplasm repository were used to study the self-compatibility and cross-compatibility in Rosa materials with different ploidy. The flow cytometry and the shoot tip chromosome counting methods were used to identify the ploidy and analyze the pollen germination rate， self-compatibility， and cross-compatibility in the Rosa with different ploidy. The results showed that there was 64 diploid Rosa among 186 Rosa， mainly including wild species and ancient roses. There was relatively few triploid Rosa， with only 21. There was 101 tetraploid Rosa， mainly including modern roses. The pollen germination rate of diploid and tetraploid Rosa ranged from 16.89% to 51.91% and 40.88% to 63.57%， with an average of 32.37% and 51.50%. However， the pollens of the triploid Rosa did not germinate at all. The results of further testing growth of pollen tubes of 53 self-pollinated Rosa and 12 hybrid pollinated Rosa showed that all 13 diploid Rosa exhibited self-incompatibility， with pollen tubes stagnating at 1/3 of the style； all 40 tetraploid Rosa were self-compatible， and the pollen tubes successfully entered the ovaries. The results of cross-pollination showed that the pollen tubes of hybrid combination with tetraploid as the male parent successfully entered the ovaries； some the pollen tubes of hybrid combinations with diploid as the paternal parent stagnated in the style. It is indicated that the tetraploid Rosa has good ability of pollen germination and strong compatibility for cross-pollination， making it highly usable in breeding hybrid Rosa.