【Objective】Normal alkanes (n-alkanes) are relatively stable components of soil organic matter. Identifying the composition and occurrence mechanisms of n-alkanes in black soil is of great significance, as it can reveal the source of organic matter and the changes in the soil-forming environment. The purpose of this study was to evaluate the influence of soil-forming processes on the n-alkane index of black soil and to explore the indicative significance of n-alkanes in black soil.【Method】In this study, samples from three typical soil formation processes of Isohumosols in the Songnen Plain were collected, including the HL profile naturally developed under relatively stable terrain conditions, the YA profile affected by erosion and accumulation under unstable terrain conditions and the SH profile with evident animal disturbance processes. The ultrasonic extraction method was utilized to extract free n-alkanes from the soil. The distribution characteristics and compound-specific carbon isotopes were analyzed. 【Result】The results showed that the HL and YA profiles were unimodal, with the main peak being C31 and the odd-even predominance, while the SH profiles were bimodal, with the main peak being C23 and C31. The ∑C25~35 and CPI values of HL and SH sections decreased with the depth of the section, while the ∑C25~35 and CPI values of the YA section increased in the buried layer. The mean δ13Calk values of HL and YA profiles ranged from -29.30 to -30.27‰ and -29.79 to -32.60‰, respectively. Our results indicate that the buried layer is found to enhance the retention of n-alkanes, while disturbance may disrupt other indicators of n-alkanes in situ records. Furthermore, the analysis of n-alkanes and their carbon isotopes suggests that soil organic matter primarily originates from terrestrial higher plants, particularly C3 plants. Since the Holocene period, herbaceous plants dominate the black soil area of the Songnen Plain, with the proportion of woody plants gradually increasing during the development of black soil. Combining the data from 14C dating, it is inferred that the climatic conditions during the last deglaciation likely played a role in the initial development of black soil, while the warm and wet climate of the Middle Holocene contributed to the maturity of black soil.【Conclusion】These results confirm that n-alkanes in black soil can reflect the impact of soil erosion-deposition and disturbance on n-alkanes. Thus, this study will provide a basis for revealing the changes in organic matter sources during the formation of black soil and reflect the soil-forming environment of black soil.