Abstract: The pollen viability of 17 ornamental trees of Prunus were studied by germinative method on agar plate. The trees are P. mume,P, mume f. rubri flora,P, armeniace,P, saliciua, P. c erasi f era vat. atro pu pura, P. japonica, P. edoensis, P. ornentosia, P. riloba, P. persica, P. persica f. alba, P. persica f. compressa, P. persica f. atropurpurea, P. persica f. rubroplena, P. persica f. albo-plena, P. persica f. rubro-densa, P. persica f. albo-densa. The result shown that the difference of pollen viability among species or cultivars was significant. The viability was affected by the pH of culture medium greatly. The optimal one is pH 5.8. The sucrose consistency in agar culture medium had no significant affectes on pollen viability.