Based on field observation and indoor immersion methods, we examined hydrological effects of litter layer and soil layer of six different densities of Cunninghamia lanceolata plantation in Rongshui Beijianghe Forest Farm of Northern Guangxi. The results showed that: (1) The litter thickness and the stock volume of six densities of Cunninghamia lanceolata plantation ranged from 3.9 to 5.7 cm and from 4.3 to 6.4 t/hm², the thickness of litter was consistent with the change of accumulation, and the order from large to small was 1 755, 1 440, 2 025, 2 700, 2 325, 975 plants/hm²; (2)The maximum water holding capacity of litter is 2.40~14.23 t/hm², and the maximum storage capacity was 5.23~11.51 t/hm². The effective storage capacity was 2.45~9.49 t/hm², of which 1 755 plants/hm² was the largest; (3) In the 0—100 cm soil layer, the soil bulk density of different densities of Cunninghamia lanceolata was between 1.19~1.28 g/cm³, and the minimum density is 1 755 plants/hm²; (4) The maximum and effective water holding capacity of six different densities of Cunninghamia lanceolat were 1 755 plants/hm², and the maximum water holding capacity was far greater than the effective water holding capacity; (5) The water holding capacity of litter and its decomposition layers had a logarithmic relationship with soaking time (R²>0.96), and the water absorption rate had a power function relationship with soaking time (R²>0.92). In conclusion, the forest with density about 1 755 plants/hm², Cunninghamia lanceolata forest showed better water conservation ability.