In order to clarify the priming effect and contribution of exogenous organic matter on CH₄ emissions, an incubation experiment was carried out with three ¹³C-labeled organic substances (glucose, acetic acid, and oxalic acid) in a paddy soil for one month. The results showed that cumulative CH₄ emissions were significantly different among different treatments, in an order of acetic acid > glucose > oxalic acid > control (P<0.05). Two-way ANOVA indicated that the decomposition of soil native organic matter was accelerated with the addition of exogenous organic matter (positive priming effect). The percentages of priming effect (PE) CH₄ from soil were about 73.3% (glucose), 71.5% (acetic acid) and 40.9% (oxalic acid) of total CH₄, respectively. Different PEs and the significantly positive correlations between CH₄production and PE demonstrated that exogenous organic matter can promote soil CH₄ emission, mainly because of their PE on original soil organic matter. The major role of exogenous organic matter on soil native organic matter decomposition may be due to their effects on soil microbial activity metabolism.