To clarify the effects of combined application of straw and bentonite on soil organic carbon(SOC)and active organic carbon fractions and their distribution ratios，as well as carbon pool management index in the 0～40 cm soil layer in dry farmland，a field experiment was conducted for three years from 2019 to 2021 at Yijianfang village，Qingshuihe county，Inner Mongolia. Four treatments were set up，including no application of bentonite and straw(CK)，single application of bentonite(T2)，single application of straw(T1) and straw combined with bentonite(T3). The results showed that soil organic carbon and activated carbon fractions decreased first and then increased(except POC content)between years，and was in the order of 10～20 cm > 0～10 cm > 20～40 cm. All treatments increased soil organic carbon and its active fraction in 0～10，10～20 and 20～40 cm soil layers compared with CK，and the straw with bentonite combined application was more effective than straw single application. In the 0～40 cm soil layer，the three-year average values of SOC，DOC，LOC，and POC increased by 7.16%～9.63%、12.35%～18.05%，15.55%～41.97% and 100.73%～127.90%，respectively，under the T3 treatment compared with CK；straw combined with bentonite(T3)treatment simultaneously increased DOC/SOC，LOC/SOC，POC/SOC and CPMI in different soil layers；There was a significant positive correlation between soil organic carbon and each fraction，with LOC having the largest correlation coefficient，indicating that LOC could better reflect the changes of SOC. It can be seen that the measure of straw return combined with bentonite in dry farming area can significantly increase the soil organic carbon，active organic carbon fraction and its distribution ratio and carbon pool managenment index，which is important for soil fertility enhancement and quality improvement in dry farmland.