Purpose: In response to the current situation of less application of muddy water irrigation in agricultural production, combined with water scarcity problems and soil salinization in arid and semi-arid areas. Methods: This study adopts indoor one-dimensional soil column infiltration to systematically analyze the effects of two sediment concentrations (rho 0: 0, rho 1: 4%), three salt contents (S0: 0.80 gkg- 1, S1: 4.81 gkg- 1, S2: 9.45 gkg- 1), and three biochar addition amounts (B0:0, B1: 1%, B2: 2%) on soil water transport, base ion composition and distribution, and leaching characteristics. Results: The results showed that: (1) The increase in sediment concentration, salt content, and biochar addition significantly inhibited the infiltration rate and wetting front migration distance, and the Kostiakov model simulated infiltration rate better than the Philip model. (2) With the increase of sand and salt content, soil moisture content decreases and electrical conductivity increases. However, the addition of biochar can increase soil moisture content by 0.99-5.31%, reduce electrical conductivity by 3.09-13.07% and 8.05-19.73%, and significantly reduce the content of various salt ions. (3) The volume of the leaching solution decreases with increasing sand content, salt content, and biochar addition. The treatment with rho 0S2B2 showed the highest leaching solution conductivity, with an average conductivity of 76.52 mScm- 1. Conclusions: This study reveals that biochar can synergistically optimize the dual effects of water retention and salt leaching inhibition in saline-alkali soil, providing a theoretical basis and technical path for the ecological improvement of saline-alkali soil.