Data set provides information about capillary pressure-saturation-relative air permeability for twenty five soil samples. And the introduction of the data source compiled in the Excel file (25 Measured data sets_relative air permeability and water retention.xlsx): 1. The data sets of Brooks and Corey (1964, 1966) were retrieved from literature by Zhenlei Yang (zlyangtamu@gmail.com). 2. The data sets of Touma and Vauclin (1986), Stonestrom (1987), and Dury (1997) were retrieved from literature by Xingxing Kuang (cugbkxx@126.com). 3. The data sets of Tuli and Hopmans (2004) and Tuli et al. (2005) were generously shared and provided by Jan W. Hopmans (jwhopmans@ucdavis.edu).