Poor rate of fruit set is a severe problem which reduces the yield of sweet cherry in warm regions, and this problem is mainly due to early ovule degeneration at high temperature. Changes of expression pattern of genes involving in ovule identity are deduced to lead to such problem during sweet cherry ovule development. In this report, sweet cherry ovule identity gene, Prunus avium L. SEEDSTICK (PaSTK), was cloned and analyzed. PaSTK has a maximal open reading frame with a length of 669 bp, which encodes a protein with 222 amino acid residues. Sequence and expression pattern analysis indicates that PaSTK is a homolog of SEEDSTICK gene, and belongs to class D gene family in plant MADS-box genes. Expression level analysis of PaSTK during the key development stages of ovary indicates that the gene expression level is not apparently changed in ovary by higher temperature or pollination, even in different sweet cherry cultivars. The stable expression level of PaSTK in ovary reveals that PaSTK gene does not affect early ovule degeneration, and is not responsible for poor rate of fruit set at warm climate.