Abstract: This paper attempts to improve the infiltration and evaporation process of soil water by adding biochar,to solve the problem of uneven seasonal precipitation and large irrigation evaporation loss in the arid area of Northwest China. It uses soil column experiments to study the mass addition ratio of 6 levels of biochar0（CK）,1%（B1）,2%（B2）,3%（B3）,5%（B5）,7%（B7）on the influence of soil wetting front,cumulative infiltration,and cumulative evaporation,and verify the applicability of different infiltration and evaporation models under the conditions of biochar addition. The results show that the more biochar is added,the more obvious the effect of slowing down the migration rate of wetting front and the depth of soil wet front migration has a power function relationship with the infiltration duration. Compared with CK treatment,the cumulative infiltration of B1,B2,B3,B5 and B7 decreases by 6.0%,11.9%,19.9%,28.0% and 36.2% respectively,indicating that biochar can significantly reduce the cumulative infiltration of soil. With the increase in biochar proportion,the inhibition of soil evaporation is more obvious. Therefore,considering the process of soil infiltration and evaporation,the optimal biochar content is 3%～5%. The simulation results of the model show that the Kostiakov model and Rose model can better describe the process of soil water infiltration and evaporation under the condition of biochar addition. This study can enrich the application scenarios of biochar,and provide theoretical reference for the practical application of biochar in the arid area of Northwest China.