Fifty sexual hybrids were obtained from 3760 single oospore isolates from pairing of two Phytophthora cactorum isolates (AP14M^r-1-52 with resistance to metalaxyl and sensitivity to chloroneb, PK9Cn^r-2-24 with resistance to chloroneb and sensitivity to metalaxyl) which were incubated on SL media for 36 days. Biological characteristics of randomly selected 32 hybrids were tested in growth rate, sexual and asexual reproduction capacity, oospore and zoospore germination rate,pathogenicity, and tolerance towards high temperature. Results were as follow, the 32 hybrids tested grew well on lima bean agar (LBA), 24 of which were the intermediate between their parents in growth rate; most of hybrids tested produced a great number of oospores on LBA or SL,37% of hybrids produced much more oospores than their parents on SL; most of hybrids produced a great number of zoosporangia in vitro, 15 hybrids were the intermediate between their parents in production of zoosporangia; oospores or zoospores of hybrids tested may germinate and create effective single oospore or zoospore isolates; the germination rate of oospores from 22 hybrids were more than 50%; the tested hybrids inoculated on apple fruits were of virulent, 16 of which were of significantly stronger pathogenicity as compared with their parents. These results show that sexual hybrids from homothallic P. cactorum were of strong fitness at population level in vitro, indicating that sexual recombination of different isolates might play a important role in enhancing the diversity of P. cactorum.