The fluxes of heat, water and other trace gases are measured directly using eddy covariance method. For eddy covariance measurements, a new calibration-free open-path trace gas analyzer, based on tunable diode laser absorption spectroscopy (TDLAS), is developed and applied for trace gas fluxes in the atmospheric surface layer. By selecting different absorption lines, different trace gases are detected. Carbon diode absorption line (near 4990 cm-1) is taken as an example. The output bandwidth of the new gas analyzer is more than 10 Hz. A comparative experiment is conducted between a reliable commercial analyzer (Li-7500) using non-dispersive infrared (NDIR) gas sensor and our new trace gas analyzer. The collected data demonstrate an excellent qualitative agreement and show that the sensitivity of our gas sensor is about 5×10-7. It is indicated that the fast sampling and high sensitivity meet the requirements of the eddy covariance method. This TDLAS trace gas analyzer is a suitable technique for determining the fluxes of trace gases using eddy covariance method.