Peatlands play a significant role in the global carbon cycle. They have been considered an important sink of carbon and account for 25%-43% global soil organic carbon stocks. Drainage has led to large losses of soil organic carbon in peatlands. However, few studies have investigated the impacts of drainage on soil organic carbon stocks in Zoige peatlands on the Qinghai-Tibetan Plateau. To reveal the spatial distribution characteristics of soil organic carbon stocks under different drainage regimes, and to provide more reliable soil organic carbon stock estimations, we surveyed the soil organic carbon stocks along a distance gradient from the ditches in Zoige peatlands. Soil bulk density and soil organic carbon stocks at different soil depths were investigated in two un-drained sites and three drained sites 130 m (D130), 200 m (D200), and 300 m (D300) away from the ditch. The soil organic carbon stocks ranged from 816.53-1030.88 tC/hm² in un-drained sites, with a mean of (923.71±107.18) tC/hm². The soil organic carbon stocks in un-drained sites were 8.1-fold higher than the China's average, and 9.4-fold higher than the global average. The mean soil organic carbon stocks in drained sites were (641.97±85.51) t C/hm² in site D130, (606.34±33.10) tC/hm² in site D200, and (473.72±43.81) tC/hm² in site D300, respectively. The mean soil organic carbon stocks of all drained sites was (574.01±66.86) tC/hm², which was 5.1-fold higher than the China's average, and 5.8-fold higher than the global average. The depth-averaged bulk density ranged from 0.28-0.73 g/cm³ with a mean of (0.53±0.03) g/cm³ in un-drained site 1, and 0.35-0.67 g/cm³ with a mean of (0.46±0.09) g/cm³ in un-drained site 2. The depth-averaged bulk density ranged from 0.56-0.78 g/cm³, 0.46-0.77 g/cm³, and 0.44-0.98 g/cm³ at D130, D200, and D300, respectively. The bulk density of the top 30 cm, 50 cm, 100 cm soil layer, and the full-surveyed depth at the drained sites were 57.53%, 48.69%, 41.79%, and 31.58% higher than those of the corresponding depths in un-drained sites, respectively. Furthermore, the soil organic carbon stocks at the top 30 cm soil layer in the drained sites was markedly higher than that in un-drained sites (P < 0.01). However, the soil organic carbon stocks at the full-surveyed depth in drained sites appeared significantly lower than that in un-drained sites (P < 0.01). The different pattern of soil organic carbon stocks between the top 30 cm soil and full-surveyed depth in drained and un-drained sites might be due to the drawdown of the water table. The peat exposed to air could be promptly oxidized and decomposed in drained sites, where the soil porosity decreased and peat layer thinned. Thus, the soil bulk density and organic carbon stocks appeared to increase in the top soil layer, while soil organic carbon stocks of the whole soil profile decreased due to the thinned peat layer.