Abstract: To seek the methods that are fast, direct, inexpensive as well as being used to assess the magnitude and spatial variability of Ks at field scale, we measured air permeability (Ka), bulk density, soil layers, directions, and plant root content under different water content, respectively by using soil air permeability measurement instrument (PL-300) in Changwu county, Shanxi province, and further Ks of undisturbed soil samples (248 cm3) were measured in lab. Results showed that soil air permeability under different influence factors have a certain change law, and a log-log linear relationship between Ka measured at the actual soil-water content (close to field capacity) and Ks were found. The Ks–Ka relationship was in agreement with an earlier predictive relationship. Compared to Loll and Iverson’s results, this method was confirmed to be feasible and practical.