Near-surface vegetation coverage of erosion-degraded forestlands is low in the red soil region of South China, which leading to serious soil erosion. Inoculation of arbuscular mycorrhizal (AM) fungi can promote vegetation growth and improve soil structure and then can reduce soil erosion. The effects of AM fungi inoculation on soil carbon, nitrogen and glomalin were investigated in erosion-degraded Pinus massoniana forestland, and two treatments were set up, including shrub planting (S), and shrub planting with AM fungi (S+AMF). The results showed that nearly one year after inoculation with AM fungi, mycorrhizal colonization rate (MCR) of S+AMF treatment was significantly higher than that of S treatment on the upper slope position and the whole slope (P<0.05). The contents of SOC, TN, SMBC, EE-GRSP and T-GRSP in the lower slope were significantly higher than those in middle slope in the S+AMF treatment (P<0.05), while there was no significant difference among slope positions in the S treatment (P>0.05). There was no significant difference in AN, SMBN and pH among different slope positions in each treatment (P>0.05). Compared with S treatment, the mean contribution rates of S+AMF treatment to MCR, SOC, TN, SMBC, SMBN, EE-GRSP, T-GRSP, AN and pH were 43.83%±15.10%, 5.33%±1.57%, 14.69%±7.92%, 27.88%±4.89%, 39.25%±4.82%, 6.90%±2.56%, 12.47%±7.95%, -13.18%±6.63%, -0.71%±2.74%, respectively. The Pearson correlation and stepwise regression analysis suggested that there was a significant positive correlation between MCR, SOC, TN, SMBC, SMBN and glomalin (P<0.05). TN, SMBC and MCR explained 80.5% variation of SOC and SOC, SMBC, SMBN and MCR explained 90.4% variation of TN, while TN, SMBN, pH and MCR explained 48.9% variation of AN, indicating that inoculation with AM fungi increased mycorrhizal colonization rate of Amorpha fruticosa Linn root system, which indirectly promoted the increase of soil carbon, nitrogen and glomalin. This study was of great significance for effectively improving the soil quality and promoting vegetation restoration in erosion-degraded forestlands.