Abstract: In view of the current limited application of muddy water irrigation in agricultural production, and considering the problems of water shortage and soil salinization in arid and semi-arid regions, this study conducted one-dimensional soil column infiltration experiments in the laboratory to investigate the effects of different salt contents (S0: 0.80 g/kg, S1: 4.81 g/kg, S2: 9.45 g/kg) and biochar addition amounts (B0: 0, B1: 1%, B2: 2%, B3: 3%) on soil water transport, salt ion distribution and leaching characteristics under clear water (ρ0: 0) and muddy water (ρ1: 4%) infiltration conditions. The results showed that the cumulative infiltration amount significantly decreased with the increase of salt content (S) and biochar (B). Compared with clear water (ρ0), the turbid water (ρ1) reduced by 18.05% to 31.57%. The medium (S1) and high salt (S2) treatments reduced by 9.40% to 18.58% and 15.38% to 23.86% respectively compared with the low salt (S0) treatment. The addition of biochar (B1/B2/B3) reduced by 0.75% to 21.16% compared with no addition (B0). The Kostiakov model (R²>0.88, S_RMSE<0.09 cm/min) was more suitable for simulating the infiltration rate than the Philip model. Its parameter K decreased with the increase of S and B, while α was the opposite. The distance of the wetting front migration (F) and time (t) conformed to the power function (F=Ctᴰ). The turbid water prolonged the time to reach the bottom of the soil column by 10.50% to 27.93%, and S and B further delayed the migration. The fitting parameters C and D were negatively exponentially correlated with S and B (R² > 0.92). The soil profile analysis shows that the moisture content decreases with depth, while the electrical conductivity increases. The turbid water reduces the average moisture content by 0.52% to 4.37%, and increases the electrical conductivity by 1.78% to 16.74%; the high salt (S2) reduces the moisture content by 9.09% to 11.59%, and causes a sharp increase in the electrical conductivity by 215.21% to 314.95%; while the biochar (B3) increases the moisture content by 2.61% to 5.53%, and reduces the electrical conductivity by 10.23% to 23.80%. Except for soil potassium ions (K⁺), the contents of soil calcium ions (Ca²⁺), magnesium ions (Mg²⁺), sodium ions (Na⁺), sulfate ions (SO₄²⁻), chloride ions (Cl⁻) and bicarbonate ions (HCO₃⁻) all increased with the increase in salt content, and the increase was more significant in the muddy water treatment than in the clear water treatment; while biochar addition significantly reduced the contents of Na⁺ and Cl⁻, and promoted the retention of K⁺ and Ca²⁺. The high salt content (S2) exacerbates salt accumulation and reduces the volume of the leaching solution. The treatment with ρ1S2B3 showed the highest leaching solution conductivity, with an average conductivity of 88.32 mS/cm. This study reveals that the sediment concentration and salt content of turbid water inhibit water transport through pore blockage and osmotic pressure effects, while biochar optimizes water salt balance by regulating ion adsorption and pore structure, providing a theoretical basis for the synergistic improvement of turbid water irrigation and biochar in saline alkali land.