A portable wind tunnel, which was designed for investigating the seed dispersal by wind, was built by the Institute of Applied Ecology, Chinese Academy of Sciences and the Experimental Center of Desert Forest, Chinese Academy of Forestry. The wind tunnel was designed to satisfy the requirements of investigations at diaspore, plant individual and landscape scales. Therefore, the experiment section was determined as 2 m×2 m and the segments were fixed by a fluctuation way. The experiments on test and evaluation of the flow field, carried out under three wind speeds of 4.6, 5.7 and 8.0 m·s^-1, indicated that the flow stability coefficient was less than 4%, the transverse uniformity was less than 7%, the turbulence was about 6%, and the thicknesses of the bottom boundary layer and side wall boundary layer were 28 cm and 15 cm, respectively. This study suggests that the wind tunnel meets the experiment requirements of seed dispersal by wind at diaspore, plant individual and landscape scales.