Lung injury occurring in the early stage of heat stroke (HS) leads to hypoxia and further aggravation of other organic damage. Lactoferrin (LF) is an iron binding protein with anti-inflammatory and antioxidant effects. This study focuses on the protection of preadministration of bovine lactoferrin (BLF) against lung injury in rats with HS. Sixty-four Sprague-Dawley male rats were divided into four groups randomly: control (CON)+phosphate-buffered saline (PBS) ( = 16), HS+PBS ( = 16), HS+low-dose BLF (LBLF) ( = 16), and HS+high-dose BLF (HBLF) ( = 16). CON+PBS and HS+PBS were preadministered 10 mL/kg PBS for 1 week. HS+LBLF and HS+HBLF were preadministered 100 and 200 mg/kg BLF for 1 week, respectively. The HS onset time and the survival rate were recorded, and bronchoalveolar lavage fluid was obtained to measure protein concentration. Lung was obtained for pathological analysis and wet/dry weight ratio measurement; later, the content of malondialdehyde (MDA), activity of myeloperoxidase (MPO), and superoxide dismutase (SOD) were measured in lung tissue homogenate. The results indicated that BLF preadministration could delay the HS onset time, enhance the survival rate, the levels of serum inflammatory cytokine and MDA content in HS+LBLF and HS+HBLF showed significant reduction compared with HS+PBS, while a significant elevation of SOD activity and reduction of MPO activity in HS+HBLF. Our results demonstrate that BLF preadministration could relieve lung injury in HS rats by enhancing thermal endurance, and alleviating serum inflammatory response and pulmonary oxidative stress damage.