Abstract: isobaric tags for relative and absolute quantitation（iTRAQ） technology was uesd. To screen the differentially expressed ovary proteins in Dolang sheep with oestrum, anestrus and pregnancy, so as to provide a basis for the research of regulation and identification of oestrum, the diagnosis of early pregnancy. In total, the study identified 4 847 proteins, 470 of which were significantly different proteins. Compared with anestrus, 18 proteins were up and 102 proteins were down in oestrum, 20 proteins were up and 60 proteins were down in pregnancy;Compared with oestrum, 50 proteins were up and 24 proteins were down during pregnancy. Such as cyclin-Y isoform X1, cleavages timulation factor subunit 1 isoform X1, follistatin-related protein 1 isoform X2, nicotinate phosphoribosyltransferase isoform X1 were up-regulated proteins; hemopexin isoform X1, apolipoprotein A-Ⅱ,nucleophosmin at down-regulated, which were related to hormones generation, regulation of oestrum, zygote production and apoptosis, early embryo attachment and embryo development. Among them, cyclin-Y isoform X1 and nicotinate phosphoribosyltransferase isoform X1 significant increased in pregnancy, compared with oestrum and anestrus. The study identified different proteins at oestrum and pregnancy of Dolang sheep based on iTRAQ proteomics techno logy, which provided new thoughts and methods to further exploring the candidate biomarkers of sheep estrous identification and diagnosis of early gestation.