To understand the mating compatibility of Pyrus ussuriensis Maxim.,we studied the fertility of pollen and conducted a hand-pollination trial in the field on some pear varieties and wild types.The results showed that about 53% of varieties among 32 tested genotypes were male sterile.Not only did the pollen vitalities in normal varieties show distinct differences,but pollen vitalities from flower forcing in a glasshouse were found to be lower than those from natural flowering in the field,which had no apparent effect on fruit setting of tested varieties.Most of the tested genotypes such as Nanguoli,Pingxiangli,and Hanxiangli showed selfincompatibility (SI).Honghuagaili could bear fruit after hand pollination,but there were abnormal seeds in its fruits.So we suggested it was a recessive SI that happened during embryo development.Longxiangli has the capacity of self-compatibility (SC) to some extent,its fruit setting rate of inflorescence could reach 23.3%.Manual self-pollination during bud flowering could improve the fruit setting rate of part tested genotypes with SI,but had no effect on the fruit setting rate 3 days after flowering.Mating between female parents with the variety selected from F1 generation showed that the majority of their combinations were compatible.There was one-way SC when Nanguoli was crossed with Hanhongli,while no fruits could be found after Hanhongli was crossed with Nanguoli.It may be related to the S-genotype or haplotype of Nanguoli.In addition,mating between the varieties derived from bud mutation with the female parent appeared incompatible.We concluded that P.ussuriensis Maxim.is similar to other grown pear systems with the characteristics of SI,the fruit setting rate of self pollination in some varieties and wild types can be improved by artificial self-pollination during bud flowering,and fruit cannot be developed through pollination between the varieties from bud mutation and the female parent.