To evaluate the water conservation capacity of Pinus tabulaeformis forest with different ages quantitatively, water balance method and comprehensive water storage method were used to investigate the rainfall redistribution, litter water-holding capacity, soil water storage capacity of three Pinus tabulaeformis stands with different ages in Liaohe source region. The results showed that: (1) During the observation, a total of 112 times rainfall were observed, cumulative rainfall was 902.2 mm, the average rainfall was 8.1mm; the light rain, moderate rain, heavy rain and torrential rain accounted for 25.2% 35.5%, 26.4% and 12.9% of the total rainfall, respectively. (2) The percentage of crown canopy interception, forest precipitation and sap flow of Pinus tabulaeformis forests in total rainfall were 24.1%, 72.9% and 3%; there was a significant positive linear relationship between forest precipitation inside and outside; with the increase of forest age, the capacity of crown canopy interception increased, and the sap flow increased first and then decreased; (3) The maximum moisture capacity of litter, the maximum of moisture absorption ratio and effective interception amount increased with the increase of forest age; (4) With the increase of forest age, the soil bulk density reduced, but the total porosity, soil infiltration rate and storage capacity increased; (5) The water conservation capacity of Pinus tabulaeformis forest with different ages performed : mature forest > nearly mature forest > middle-aged forest. In different aged Pinus tabulaeformis stands, the ability of rainfall distribution and retention capacity and water conservation capacity increased with the succession.