Abstract: As a typical rain-fed agricultural area, it is crucial to improve soil water retention and infiltration performance under seasonal drought conditions in southern red soil sloping farmland．Four test plots with 0%、1%、3% and 5%（by mass ratio）were set up, to investigate effects of different biochar additions on soil infiltration performance in red soil sloping farmland, and selecte optimal soil infiltration models．Results showed that compared to control without biochar addition, biochar addition treatments' soil porosity significantly increased by 0.91%～3.41%, soil bulk density significantly decreased by 1.67%～6.53%, soil moisture content significantly increased by 6.62%～23.93%, and treatment with 5% biochar addition enhanced the best soil water retention．With increasing biochar amount, soil initial, steady, and mean infiltration rates increased by 27.22%～80.41%, 25.10%～81.10%, and 26.28%～82.06%, respectively, and cumulative infiltration under different biochar additions was shown as 0% > 1% > 3% > 5%．Comparative analysis of fitting results of three soil moisture infiltration models（Philip, Kostiakov, Horton）indicated that Kostiakov model outperformed the others．It suggested that biochar application could suppress soil moisture infiltration during rainfall and irrigation processes, reduce water loss, and enhance soil water retention capabilities．It could be used to provide a reference for improving soil water retention and enhancing soil structure under seasonal drought conditions．