Abstract: Obtaining accurate soil organic carbon (SOC) content in the Xingkai Lake Plain and the main factor controlling its spatial variation is greatly significant for controlling and restoring the SOC content and achieving sustainable agricultural development. This study investigated the spatial distribution characteristics of the SOC content in the Xingkai Lake Plain and their control factor based on 4,151 topsoil samples collected at a depth of 0~20 cm in the field. Moreover, it compared the effects of soil parent materials, soil texture, soil type, land use type, and land reclamation duration (year) on the spatial distribution of the SOC content in the plain through geostatistical and regression analyses. The results are as follows. The SOC content in the topsoil of the study area is 0.35%~14.49% (average: 2.80%). It has a coefficient of variation of 0.44, indicating moderate spatial variations. It has a nugget-to-sill ratio of 47.06%, indicating that its spatial distributions are affected by both structural and random factors. It is low in the middle and west and is high in the east and north overall. All these five factors have significant effects on the SOC content (P<0.01). Among them, soil parent materials, soil type, land use type, and land reclamation duration can independently account for 6.8%, 3.8%, 9.2%, and 3.3% of the spatial variations in the SOC content, respectively. By contrast, soil texture can independently account for 30.1% of the spatial variations of the SOC content, which is far greater than that of the other four factors. Therefore, soil texture is the main control factor in the spatial distribution of the SOC content in the study area.