The purposes of this study were to understand the water conservation capacity of litter of Cryptomeria fortunei plantation with different forest ages, and to provide basis for the determination and implementation of forest soil and water conservation measures. Five age groups of C. fortunei plantation in Pingba Dapo Forest Farm of Guizhou Province were chosen as object in October 2018. The water holding capacity of litter was studied by drying method and laboratory immersion method, and the water conservation function of litter in five age groups was evaluated comprehensively by entropy weight method. The results showed that:(1) With the growth and development of C. fortune plantation, litter reserves and water holding characteristics showed a trend of first increasing and then decreasing, showing that mature forest was the largest and young forest was the smallest. The litter thickness, volume, maximum water-holding capacity, maximum water-holding rate, effective storage capacity and effective storage rate of mature forest were 7.40 cm, 2.21 t/hm², 6.46 t/hm², 265.14 t/hm², 3.94 t/hm², and 175.74% respectively. (2) The water conservation capacity of litter in five age groups was calculated by the method of entropy weight, which was:mature forest (11.46) > near-mature forest (10.79) > over-mature forest (8.26) > middle-aged forest (4.83) > young forest (3.94). The mature forest had the largest water conservation capacity.