This study investigated aerially seeded Pinus massoniana plantations to analyze soil carbon and nitrogen distribution characteristics and the relationship with litter quality under two understory vegetation types (Dicranopteris and Graminoid) by using matched-pair t test and redundancy analysis. The results showed that:(1) At soil depths of 0-10 and 10-20 cm, soil organic carbon, microbial biomass carbon, dissolved organic carbon, total nitrogen, available nitrogen, microbial biomass nitrogen, and dissolved organic nitrogen were significantly higher for graminoid than for Dicranopteris (P < 0.05). However, at depths of 10-20 cm and 20-40 cm, the regularities of two understory vegetation types soil carbon and nitrogen indicators were different, but not significantly (P > 0.05). (2) The C content and C/N ratio of the semi-decomposed and undecomposed litter layer were significantly higher for Dicranopteris than for graminoid (P < 0.05). The N content of semi-decomposed and undecomposed litter layer of Dicranopteris were significantly higher than for graminoid (P < 0.05). The C content and C/N ratio of the undecomposed litter layer were significantly higher than of the semi-decomposed litter layer, and the N content of the semi-decomposed litter layer was significantly higher than of the undecomposed litter layer (P < 0.05). (3) At 0-10 cm, the C/N ratio and C content of litter were significantly negatively correlated with soil carbon and nitrogen (P < 0.05), and the N content was not significantly correlated with soil carbon and nitrogen (P > 0.05). At 10-20 cm, the semi-decomposed litter C/N ratio of Dicranopteris was significantly correlated with soil carbon and nitrogen (P < 0.05). The litter C content of graminoid was significantly correlated with soil carbon and nitrogen (P < 0.01). The lower litter C/N ratio of understory vegetation was associated with a faster litter decomposition rate, which was helpful for accumulating soil nutrients. The litter C/N ratio of graminoid was lower than that of Dicranopteris, explaining why the soil carbon and nitrogen indicators were significantly higher for graminoid than for Dicranopteris.