Forest ecosystem is the largest carbon reserve pool in terrestrial ecosystem.Under climate change,temperature changes can influence forest ecosystem carbon balance process.In this study,we choose Changbai mountain temperate mixed forest ecosystem (CBS).Using CO₂ flux data and microclimate data observed from 2003 to 2008,we analyzed the responses of gross primary productivity (GPP),ecosystem respiration (Re),and net ecosystem exchange of CO₂ (NEE) to temperature (air temperature and 5 cm depth soil temperature).The results showed that the seasonal variation of carbon exchange is very obvious in this forest ecosystem.Maximum carbon budget appeared in the summer.The maximum GPP in July.The maximum Re mainly appear in the August.The NEE reach maximum negative value in June or July.The GPP and Re increased with the rise of temperature (air temperature and 5 cm depth soil temperature) exponentially at daily scale and monthly scale.The response of NEE to temperature can be divided into two stages at daily scale and monthly scale.At first stage,NEE increased with the rise of temperature,which indicated carbon emissions increase with temperature increase.When the temperature was larger than the critical temperature,NEE decreased with the temperature increase.The result indicated that net carbon uptake increase with temperature.The optimum temperatures for GPP,Re,and NEE changed with changes in annual mean temperature.The annual GPP and Re in CBS increased with the rise of annual mean air temperature.As a result,the net carbon uptake decreased with the rise of temperature without considering other environmental factors effects under climate change.