Soil organic carbon（SOC） is a large component of the global carbon cycle, and related to atmospheric CO2 levels because soils have the potential for C release or sequestration, depending on land use, land management and climate. In addition, SOC is vital for ecosystem function, having the greater influences on soil structure, soil fertility, water holding capacity, cation exchange capacity and the soil′s ability to form complexes with metal ions and store nutrients. The influence of landuse changes on SOC is not only relevant to vegetation type, but also to its growth phase. As an important landuse pattern on Loess Tableland, apple orchard is inconsistent with cereal field in the input and output forms of SOC. In order to understand the influence of the transition of landuse pattern from cereal field to apple orchard on the SOC pool, as well as the characteristics of spatial distribution and variations of SOC in different growth periods of apple orchards, SOC was measured at the distances of 1.0m, 1.5m and 2.0m from each apple tree core in 5a, 10a, 15a and 20a apple orchards on tableland and slope terrace of the Loess Tableland. Soil samples were collected by Soil Drill and the SOC was measured by LiquiTOCⅡ analyzer. Results showed that the SOC contents in 5a, 10a, 15a and 20a apple orchards on tableland were 6.39 g/kg, 6.46 g/kg, 6.66 g/kg and 6.47 g/kg, respectively, and on slope terrace, were 5.83 g/kg, 6.05 g/kg, 6.54 g/kg and 6.09 g/kg, respectively. The SOC content on tableland was significantly higher than that on slope land for the same age apple orchards（P＜0.05）, and however, the SOC content rank of apple orchard on tableland and slope land had the same order. Along apple tree core in the horizontal direction, the SOC content ascended at 5a, declined at 10a, and steadied at 15a and 20a. The horizontal distribution patterns of the SOC on slope land were similar to the same age apple orchard on tableland. In vertical direction, the SOC contents of 0-10cm, 10-20cm, 20-50cm and 50-100cm layers in 5a, 10a, 15a, and 20a apple orchards on tableland were higher than those on slope land, respectively. The SOC content in different age apple orchards varied widely at the 50-100 cm layer on slope land and slightly in the 20-50cm layer on slope land and 50-100 cm layer on tableland. Based on our experiment, the SOC content did not decrease in the 5a to 20a apple orchards, and on the contrary, increased in the deeper soil layers.