Abstract: Evaluating CO2 storage flux may help us to improve the calculation accuracy of net ecosystem CO2 exchange (FNEE). Based on data of two consecutive years from an eddy covariance system and a vertical CO2 profile system in a tropical seasonal rainforest in Xishuangbanna, southwest China, CO2 storage flux was calculated by two methods, eddy covariance (Fs-EC) and profile (Fs-PM) methods. Results show that: 1) Comparing with eddy covariance method, diurnal variation of CO2 storage flux calculated by profile method could directly reflect the spatial-temporal variation of CO2; 2) Total amount value of CO2 storage flux calculated by profile method was -0.04 t/(hm2•year), and the value calculated by eddy covariance method was -0.17 t/(hm2•year); 3) Under complex terrain and tall forest conditions, with a large concentration gradient of CO2, profile method for calculation of CO2 storage flux had an advantage over eddy covariance method.