Soil organic carbon pool is the largest carbon pool in the terrestrial ecosystem, and thus its small change can result in a significant change in atmospheric CO₂ concentration. The input of plant-derived carbon can accelerate or mitigate the decomposition of soil organic carbon (SOC) through the priming effect, and eventually affect SOC balance. To investigate the impacts of labile organic carbon input on the priming effect and clarify the underlying mechanisms, a ¹³C labeling experiment with different amount of glucose inputs (0, 100, 200 and 400 mg C/kg) were carried out in this study. The experimental soils were collected from three different forest soils (the evergreen broadleaf forest, broadleaf and coniferous mixed forest, and Pinus massoniana forest) in Wuyi Mountain. The results showed that the impacts of glucose input on the priming effect were dependent on both the amount of glucose input and forest type. The input of glucose inhibited the decomposition of SOC in the three forest soils (i.e., a negative priming effect). The magnitude of the priming increased with increasing the input of glucose in the broad-leaved forest and coniferous and broad-leaved mixed forest, whereas the response of the priming magnitude to the glucose input was not significant in Pinus massoniana forest soil. However, the priming effect in Pinus massoniana forest soil was significantly higher than that in the other two forest soils. The results indicated that the input of labile organic carbon could inhibit the mineralization of SOC and formed a negative excitation effect. The priming effect in broad-leaved forest soil was related to soil available N and the ratio of glucose application rate to microbial biomass carbon, while the priming effects in coniferous and broad-leaved mixed forest and Pinus massoniana forest soil were related to actinomycetes and fungi, respectively.