The Osmia cornifrons plays an important role in pollinating fruit trees, such as apple trees. To better understand diapause and oviposition in O. cornifrons, we investigated the correlation between the ovarian development and secretion level of OcVg protein in hemolymph. During ovarian development in wintering the number of oocytes progressively increased in comparison with the length of the ovaries and the oocytes. After emergence, the oocyte and ovary sizes developed until 6 days after emergence and declined after 6 days, but the number of oocytes decreased gradually. The secretion level of OcVg protein in hemolymph revealed that during wintering, the secretion level increased from 1 month to 2 months and then stagnated after 2 months. After diapause, the secretion level increased gradually until day 6 of the newly emerged adult from cocoon stage, and thereafter gradually declined, remaining detectable until day 30 of the adult stage. The correction analysis between ovarian development and OcVg secretion level in hemolymph found that in wintering, the number of oocytes was positively correlated to OcVg secretion level. After diapause, the ovary and first oocyte lengths and the number of oocytes showed significant changes in OcVg secretion level and positively correlated with OcVg secretion level, respectively. These results suggest that there is a significant interaction between ovarian development and the secretion level of OcVg protein and the pattern of ovarian development and secretion of OcVg protein are stage-specific in the O. cornifrons female.