In order to investigate the soak characteristic of litters in southern fast-growing tree species, this experiment used pine, China fir, eucalyptus and Castanopsis hystrix to study the water quality alteration of them. The results showed that pH value of soak solution of eucalyptus was lower than others, and odour was stronger and more durable. Meanwhile the chromaticity color was very high in the beginning of the immersion, but decreased with the increase of soaking time, in the end lower than soak solution...