Crimean-Congo hemorrhagic fever virus is a tick-borne virus that causes severe hemorrhagic symptoms with an up to 50% mortality rate in humans. Wild and domestic animals, such as sheep, cattle and goats, are the reservoirs. The recombinant nucleoprotein-based Crimean-Congo hemorrhagic fever virus antibody detection systems for sheep sera were developed by enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescence assay techniques. The samples used for evaluation were 80 sera collected from sheep in a Crimean-Congo hemorrhagic fever-endemic area (western part of the Xinjiang Uygur Autonomous Region) and 39 sera collected from sheep in a disease-free region (Shandong province, eastern China). The ELISA and indirect immunofluorescence assay using recombinant nucleoprotein of the virus proved to have high sensitivity and specificity for detecting the immunoglobulin G antibodies to the virus in sheep sera. Within this limited number of samples, the recombinant nucleoprotein-based ELISA and indirect immunofluorescence assay are considered to be useful tools for seroepidemiological study of virus infections in sheep sera.