Abstract:[Objective] The characteristics of water conservation capacity of the mixed combination models of Mytilaria laosensis and Castanopsis hystrix were explored, and the best mixed combination mode of water conservation capacity was selected, in order to provided a scientific basis for the construction, operation and management of water conservation forest in Xijiang River basin. [Methods] Nine mixed plantation patterns with three mixing proportions (i.e., 1∶3, 2∶2, and 3∶1) and three mixing modes (i.e., interplant mixing, strip and row mixing, and block mixing) of M. laosensis and C. hystrix were selected, and the pure plantations of both species served as controls. The differences in the water conservation capacity of litter and soil among the eleven planting models were evaluated, and the mixed plantation with the optimal water conservation capacity was identified using an entropy weight TOPSIS (technique for order preference by similarity to an ideal solution) model. [Results] ① The biomass, natural water storage, effective water interception, and maximum water interception in the litter layer ranged from 1.17 to 4.21, 0.38 to 2.29, 5.15 to 10.58, and 6.40 to 13.37 t/hm2, respectively. These indices were positively and significantly correlated with the percentage of M. laosensis in the plantations (p<0.05). Compared to interplant mixing and block mixing, the strip and row mixing of the plantations yielded higher biomass and effective water interception in the litter layer. ② The natural moisture storage, capillary water storage, non-capillary water storage, and saturated water storage in soil at a depth of 0—30 cm ranged from 756.14 to 1 007.21, 1 130.73 to 1 388.40, 117.96 to 422.63, and 1 444.70 to 1 590.66 t/hm2, respectively. Capillary and non-capillary water storage differed significantly among the plantations and were positively correlated with the percentage of M. laosensis in the plantations (p<0.05). ③ The mixed plantation of M. laosensis and C. hystrix with a ratio of 3∶1 and strip and row mixing exhibited the optimal water conservation capacity. The water conservation capacity of the other plantations ranked as follows: pure plantation of M. laosensis, other mixed plantation patterns, and pure plantation of C. hystrix. [Conclusion] The water conservation capacity of the mixed plantation of M. laosensis and C. hystrix was, to a certain extent, better than that of each pure plantation in the young stand stage, which was influenced by the mixing proportions and modes.