Seasonal influence on the developmental ability of porcine embryos was studied by comparisons of the number of cumulus-oocytes-complexes (COCs) per ovary pair and meiotic maturation ability of oocytes in different seasons; and by the observations on developmental competence of the parthenogenetic oocytes and ckoned embryos collected from different seasons. We found that the number of COCs per ovary pairs was significantly higher in spring compared to the other seasons ( P＜0.05). However, no significant difference was found in the rate of oocytes progressing to M Ⅱ in four seasons ( P＜0.05 ). In addition, the rate of blastocyst formation of parthenogenetic embryos in summer was obviously declined compared to the other seasons (P＜0.05), and an increased blastocyst rate of cloned porcine embryos was found in spring compared to autumn and winter (P＜0.05). The results suggest that there should be a seasonal influence on the developmental competence of porcine embryos.