[Objective] The coupling relationship between undecomposed leaf litter traits and water conservation ability of 11 major tree species in Northeast China was explored, and their water retention and water loss processes were analyzed, in order to provide theoretical basis for clarifying the water conservation ability of main tree species in this area. [Methods] A total of 11 common tree species in Northeast China were used as the research object. The water holding and loss characteristics of undecomposed leaves were determined by indoor immersion and water loss experiments, and the physical and chemical properties of 12 kinds of leaves were then determined by vernier calipers, scanners, elemental analyzers, Klason method, and concentrated acid hydrolysis sugar determination method. The relationship between leaf traits and leaf water conservation ability was analyzed using regression analysis. [Results] The maximum water holding capacity, effective retention capacity, water loss ratio, and water loss rate of undecomposed litter of 11 species showed significant differences (p<0.05). The maximum water retention rate in descending order was Tilia mandshurica, Betula platyphylla, Tilia amurensis, Larix gmelinii, Fraxinus mandshurica, Juglans mandshurica, Quercus mongolica, Populus×canadensis, Pinus sylvestris var. mongolica, Pinus koraiensis, Picea koraiensis, and it was significantly positively correlated with the specific leaf area. In addition, there was a significant negative correlation between leaf thickness and leaf shape index (p<0.05). At 24 h, the water loss rates were (from low to high) Picea koraiensis, B. platyphylla, T. amurensis, T. mandshurica, Pinus koraiensis, Q. mongolica, F. mandshurica, Populus×canadensis, Pinus sylvestris var. mongolica, L. gmelinii, and J. mandshurica. The water loss rate was significantly positively correlated with leaf length, specific leaf area, and rough degree (p<0.05). [Conclusion] Specific leaf area was the most important leaf character affecting water conservation ability of undecomposed leaf litter, followed by leaf length, leaf thickness, leaf shape index, and roughness. T. mandshurica, B. platyphylla, and T. amurensis are tree species showing an excellent water conservation capacity of undecomposed litter.