In order to study the impact of aboveground/underground litter input change on the release of CO₂ in Pinus yunnanensis forestland. From March 2018 to February 2020, a litter addition and removal experiment (DIRT) was carried out on the Pinus yunnanensis forest in the Mopan Mountains in central Yunnan Plateau. Treatments include normal litter input (CK), double litter (DL), removing aboveground litter (NL), removing organic layer and A layer (O/A-Less), no root inputs (NR), and removing aboveground litter and root inputs (NI). The Li-6400 portable photosynthesis meter (equipped with Li-6400-09 soil respiration chamber) and the TRIME-PICO 64/32 soil temperature and moisture meter were used to measure the monthly CO₂ flux (R_s), soil temperature, and soil moisture (15 cm) of different treatment plots. The results show that: (1) the CO₂ flux of the six treatment plots showed obviously monthly changes, with the highest from July to August and the lowest from January to April. The average performance was R_s(DL) > R_s(CK) > R_s(NL) > R_s(NR) > R_s(O/A-Less) > R_s(NI). (2) Compared with CK, the CO₂ flux of the DL plot increased by 29.12%, while the CO₂ flux of the ground litter removal and underground root plots were significantly reduced, and the average change of the CO₂ flux was α(NR)=-28.85%, α(NI)=-53.14%, α(O/A-Less)=-38.46%, α(NL)=-13.29%. (3) There were significantly monthly changes in soil moisture and soil temperature in the six treatments (P<0.01). The soil moisture in NL and O/A-Less was significantly lower than that in CK, while there was no significant difference between the remaining treatments and CK. The soil temperature between different treatments showed that both NR and NI were significantly higher than CK, and there was no significant difference between the other treatments and CK (P>0.05). (4) The CO₂ flux in different treatment plots was significantly exponentially correlated with soil temperature (P<0.01), but not significantly correlated with soil moisture in NI and O/A-Less treatments (P>0.05). Compared with CK (soil respiration temperature sensitivity Q₁₀=2.39), NI, O/A-Less and NL treatments improved Q₁₀, while NR and DL treatments reduced Q₁₀, which were 3.86, 3.56, 2.48, 2.32, and 2.01. The two-factor model of forestland CO₂ flux and soil water-heat factor under different treatments can better explain the changes of forestland CO₂ flux. The change of litter input has a significant effect on the forestland CO₂ flux by changing the forestland soil carbon input and soil environmental factors.