The loss of organic carbon during passage through the continuum of inland waters from soils to the sea is a critical issue for the global carbon cycle. However,the amount of organic carbon mineralized and released to the atmosphere during its transport remains an open question,hampered by the absence of predictors of organic carbon mineralization rates. The lake water level can be affected by human disturbance and climate change,and thus change the mineralization of the sediment organic carbon. The primary objective of this study was to study the influence of different water level gradients on the mineralization of sediment organic carbon in a saline lake in arid region. Sediments at 0-50 cm depth were sampled from Lake Barkol. The mineralization rates of sediment organic carbon were measured by Li-COR 8100A under five underground water level treatments (T1,T2,T3,T4 and T5 represent underground water level 0,-9,-23,-34 and -45 cm) were settled and sediment organic carbon mineralization rates were measured by Li-COR 8100A. Results showed the mineralization rates of sediment organic carbon under T1,T2 and T3 treatments were higher (0-10 d) at the beginning of the experiment,and then decreased slowly. The carbon mineralization rates under T4 and T5 treatments increased firstly and then decreased. The mineralization rate of organic carbon under T1 treatment was 1.09,3.31 and 3.57 times higher than that under T2,T4 and T5 treatments,respectively. The cumulative mineralization of sediment organic carbon under different treatments is T3>T1>T2>T4>T5. The ratios of cumulative mineralization of organic carbon (C_t) to total sediment organic carbon (C_0) (C_t /C_0) are ranged from 1.2% to 4.4%,and the ratios of potential organic carbon emissions (C_i) to C_0 (C_i /C_0) are ranged from 1.8% to 4.5%. The decrease of underground water level reduced the mineralization constant (k value) of sediment organic carbon. The k value under T1 treatment was max (0.137 d),and that under T4 treatment was lowest (0.032 d) . The best fitting model explaining the relationship between sediment organic carbon mineralization rate and water level (x,cm) was C_r = 0.008x+0.488. There were significant positive relationships between organic carbon mineralization rate and sediment temperature at 5 cm depth. Water level had significant effect on the temperature sensitive of sediment organic carbon mineralization (Q10) . The Q10 was highest under T5 treatment (2.92),followed by T4 (2.54),and the T1 treatment had the smallest value (1.92) . These results indicated that the decrease of underground water level would reduce the mineralization rate of organic carbon and increas Q10 . The continuous decline of underground water level inhibits organic carbon mineralization,which may be a mechanism to maintain the stability of carbon pools of lake sediment in arid regions.