The soil of the Castanopsis kawakamii forest in the southern foot of Taihang Mountain was selected as the research object. Four treaments,the control ( CK),the litter ( DL),the litter removal ( NL),the litter removal and the root system ( NI) were set up. The changes of available nitrogen content and soil bulk density in 0 ~ 10,10 ~ 20 and 20 ~ 30 cm soil layers were measuredto explore the the effect of input changes of litter and roots on soil available nitrogen under the background of global change. The results showed that the soil available nitrogen content of Quercus acutissima forest decreased with the deepening of soil layer,and showed the trend of 0 ~ 10 cm > 10 ~ 20 cm > 20 ~ 30 cm under all treatments. There was significant or very significant linear negative correlation between bulk density and available nitrogen content. The soil available nitrogen under CK and DL treatments showed obvious seasonal variation dynamics,lower in autumn and winter,and higher in summer; the litter accumulated in autumn in the first year was mainly decomposed in the next year,and the difference between different treatments began to appear 5 months after the beginning of the experiment ( January of the next year); compared with CK,DL increased soil available nitrogen content,while NL and NI decreased the available nitrogen content,and the soil available nitrogen content of root removal treatment ( NI) was higher than that of root retention treatment ( NL) under the same litter removal condition. The difference between different treatments was obvious in 0 ~ 10 cm and 10 ~ 20 cm soil layers. The soil bulk density of 20 ~ 30 cm soil layers was not significantly affected by litter treatment and time change. The response of soil available nitrogen content to different treatments was relatively lagged behind. The results showed that the effect of litter input change on soil available nitrogen content was greater than that of underground roots,and the soil physical properties such as bulk density changed synergistically.