ObjectiveTo investigate the effects of thyme herbal tea （BLX） on the proliferation of human coronavirus OC43 （HCoV-OC43） in vitro and in vivo. MethodThe chemical composition of BLX was analyzed by UPLC-MS. The cytotoxicity of BLX in HRT-18 cells and the effect of BLX treatment on the proliferation of HCoV-OC43 in cells were analyzed. Copies of viral gene were detected by real-time PCR. The effect of BLX treatment on the life cycle of HCoV-OC43 was detected by time-of-addition assay. The maximum tolerated dose of BLX and the influences of BLX on the body weight and survival time of suckling mice infected with HCoV-OC43 were determined. The expression of viral protein in the brain and lung tissue was analyzed by immunohistochemistry. ResultThere were 11 chemical components identified in BLX by UPLC-MS. BLX showed the 50% cytotoxic concentration （CC₅₀） of （13 859.56±319） mg·L^-1， the median inhibitory concentration （IC₅₀） of （1 439.09±200） mg·L^-1， and the selection index of 8.26-11.44 for HCoV-OC43 in HRT-18 cells. Compared with the cells infected with HCoV-OC43， BLX at the concentrations of 1 500， 1 000， 500 mg·L^-1 inhibited the proliferation of this virus （P<0.05， P<0.01）. BLX exhibited antiviral effect in the early stage of virus infection， and the inhibition role in the attachment stage was more significant than that in the entry stage （P<0.05）. In the suckling mice infected with HCoV-OC43， BLX at 1200 and 600 mg·kg^-1·d^-1 alleviated the symptoms， prolonged the survival period， reduced the death rate， and down-regulated the mRNA level of nucleocapsid protein in the mice. Moreover， BLX at 1 200 mg·kg^-1·d^-1 down-regulated the expression of nucleocapsid protein in the brain （P<0.01） and the lung （P<0.01）. ConclusionBLX contained multiple antiviral ingredients. It inhibited the proliferation of HCoV-OC43 both in vitro and in vivo by interference with viral attachment. This study provides theoretical reference for the treatment of acute respiratory tract infection with HCoV-OC43 and for further development and application of BLX.