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In the global ecosystem, the slow decomposition of coniferous forest litter has caused a number of ecological problems, among which is the decay of China’s <i>Pinus massoniana</i> litter. It has been pointed out that converting pure <i>P. massoniana</i> plantations into mixed forests with broadleaf species can improve ecosystem services. Therefore, the selection of mixed species is key for the success or failure of the conversion of near-natural forests. In this study, from the perspective of apoplastic decomposition, the leaf litter of <i>P</i>. <i>massoniana</i> was mixed with three common native broadleaf species, namely <i>Choerospondias axillaries</i>, <i>Cinnamomum camphora,</i> and <i>Cyclobalanopsis glauca,</i> using an indoor incubation method to systematically analyse the differences in the decomposition rates of apoplastic material in each mixture, and to provide a theoretical basis for the selection and mixing of tree species for the management of near-natural forests in <i>P</i>. <i>massoniana</i> forests. After 175 days of indoor incubation of the foliar litter under dark conditions at 25 °C, the residual dry matter of the mixed apoplastic litter of <i>P</i>. <i>massoniana</i> and the three broadleaf trees was lower than that of <i>P</i>. <i>massoniana</i>. It indicated that the incorporation of broadleaf apoplastic foliage promoted litter decomposition, with the most pronounced effect in the case of admixture with <i>C</i>. <i>Camphora</i>. Compared with the group of pure <i>P</i>. <i>massoniana</i> alone, the remaining mass and residual rate decreased by 0.56 g and 9.45%, respectively. The regression equation of Olson’s negative exponential decay model showed that the <i>P</i>. <i>massoniana</i> + <i>C</i>. <i>Camphora</i> mixture had the fastest decomposition rate (k) of 1.305, an increase of 0.237, a decrease in half-life of 0.11 years, and a decrease in turnover period of 0.49 year, compared to the <i>P</i>. <i>massoniana</i> alone group. Most of the measured values throughout the incubation period were significantly lower than the predicted values, suggesting that there was a non-additive and synergistic effect of litter mixing.