Abstract: To explore the law of the air permeability coefficient of remolded loess,we modified the conventional triaxial apparatus to achieve the basic requirements of the loess air permeability test. The device expanded the maximum negative pressure difference generated by the water tank through the water pipe,and solved the problem of gas leakage from the edge of the sample using water pressure balancing air pressure. We calculated the air permeability coefficient under standard atmospheric pressure and standard temperature(20℃)through the temperature,measured water volume,and pressure indication obtained from the air permeability tests. We used the device to investigate the gas permeability of the remolded loess samples and the influencing factors such as permeability diameter,void ratio,water infiltration time,and saturation,and the sample size were D=38mm,H=76mm and D=50mm,H=100mm,respectively(D and H denote diameter and height of the sample,respectively). We also compared the differences in the gas permeability coefficients under the different sizes and analyzed the possible reasons for the changes in the air permeability coefficients. The results show that the gas flow in remolded loess test can be described by Darcy's law,and the air permeability coefficient has a certain correlation with the above factors. The soil structure obviously affects its air permeability coefficient. And the sample with a size of D=38mm and H=76mm is more suitable for the investigation of the air permeability coefficient of remolded loess.