In this study ,we prepare a Co3 O4 seed layer and thin film on an FTO substrate using spin-coating and hydrothermalmethods ,respectively. Wethen hydrothermallygrow Fe2 O3 nanorods on the Co3 O4 thin film to obtain high-quality Co3 O4/Fe2 O3 heterojunction composite materials. By changing the concentration of the Fe2 O3 precursor solution ,we can alter the contents of the Fe2 O3 components in the heterojunction composite materials. Results indicated thatFe2 O3 nanorods covered the Co3 O4 thin film with a network structure. With an increase in the Fe2 O3 precursor solution concentration ,the response of the Co3 O4/Fe2 O3 heterojunction composite materialto ultravioletlightgradually increased. When the concentration of the Fe2 O3 precursor solution was 0. 015 mol/L ,the heterojunction composite material exhibited good photoelectric stability ,a high response rate (12. 5 mA/W) ,and a high detection rate (4. 4×1010 Jones) .