Abstract: In order to better understand the regional climate change, it is necessary to quantify the CO₂ flux over agricultural ecosystem. CO₂ fluxes are collected directly by using eddy covariance over a rice paddy in the summer of 2001 and over an inhomogeneous crop surface in the summer of 2002 respectively. On average, daytime absorption and nighttime release of CO₂ flux by the rice paddy are 55.16 g· m^-2·d^-1and 14.19 g·m^-2·d^-1, and by the inhomogeneous crop surface are 22.67 g·m^-2·d^-1and 12.40 g·m^-2·d^-1. Rice paddy and the inhomogeneous crop surface are sinks of atmospheric CO₂. China is a great agricultural country, increasing the area of rice paddy will help CO₂ deposition, and will slow down increase of atmospheric CO₂ and greenhouse effect. In addition, the relationship between daytime absorption of CO₂ flux and Photosynthetically-active radiation is investigated for the rice paddy, and resulting a negative correlation. Hopefully the results obtained in present work will provide an important basis for numerical modeling of CO₂ flux between atmosphere and land。