Soil salinization has been a main factor to restrict the agricultural development in Xinjiang. In recent years, biochar has played an important role in improving soil quality. To study the effects of different biochar application amounts on soil properties and salt content, the cotton-sugarbeet intercropping field experiments were conducted under plastic filmmulched drip irrigation in the saline-alkali soils in Xinjiang, China from 2018 to 2020. The irrigation pattern of “one plastic film, two drip lines, and four rows of cotton plants” was referred to the local mode. The biochar application amounts were 0t/hm2, 10t/hm2, 50t/hm2 and 100t/hm2 in 2018. And biochar application amount of 25t/hm2 was added in 2019. Based on the results in 2018 and 2019, the biochar application amount were 0t/hm2,10t/hm2, 25t/hm2 and 30t/hm2 in 2020. The biochar was added to the top 30cm and then mixed with soils. Soil samples at different depths were collected during growth periods to measure the electronic conductivity, pH value and soil organic matter. The effects of different biochar application amounts on soil pH value, organic matter and salt content were analyzed. The results showed that the application of biochar significantly reduced soil pH value for the 0~30cm soil layer. The reduction was directly proportional to the biochar application amounts. Biochar reduced the pH value for 30~40cm soil layer, but the effect was insignificant. Due to rich organic matter contents in biochar, the soil organic matter was increased by 31.8%~135.8% for the biochar applied treatments. In the vertical direction, the soil salt content in shallow layer was larger than that in the deep layer. In the horizontal direction, the soil salt content in the no mulched zone was higher than that under the emitter. Application of biochar promoted the leaching of salt. When the biochar application amount were 10t/hm2 and 25t/hm2, the salt leaching rate was ranged in 14.7%~22.3%, which was higher than that of other treatments. Taking the salt leaching and economic cost in biochar into consideration, the appropriate biochar application amount was recommended to be 10t/hm2. The research result can provide some reference for application of biochar to improve salinealkali soil in Xinjiang.