The effects of different biochar mixing amounts on the evaporation characteristics of brackish water were investigated by centrifuge test and indoor soil column simulation test. Three biochar mass addition ratios (B₀, B₂ and B₄) and four brackish water salinity ratios (W₀, W₁, W₃ and W₅) were set up in the experiment. The effects of different treatments on soil water characteristic curve, pore distribution, cumulative evaporation, salt transport and daily variation of soil temperature under brackish water evaporation were analyzed, and the evaporation model was used for fitting analysis. The results showed that the combined application of biochar and brackish water could improve soil water holding capacity of soil and increase the proportion of larger and smaller pores in soil; The cumulative evaporation of soil water first decreased and then increased with the increase of biochar mixture, when the biochar mixture was 2%, brackish water evaporation could be inhibited better; Rose evaporation model could fit brackish water evaporation well; Biochar mixing in soil could reduce the surface accumulation of salt and make it evenly distributed in soil; Biochar could effectively reduce the diurnal variation of soil temperature; With the same amount of biochar application, brackish water with a salinity of 3 g/L could reduce the average soil temperature of 0-10 cm and increase the average soil temperature of 10-50 cm. Taking all the indexes into consideration, the biochar and brackish water treated with B₂W₃ are more suitable for farmland application, which provides a theoretical basis for better utilization of brackish water irrigation in arid areas of Northwest China.