[Objective] The contact angle hysteresis characteristics of silty particles were studied to understand the interface characteristics in the process of soil humidification or dehumidification, as well as to provide the corresponding experimental basis for the establishment of a discrete element contact model.[Methods] The initial contact angle and dynamic contact angle on the surface of soil particles were measured by the sessile drop method, and the contact angles between soil particles and pore water under the condition of humidification and dehumidification were measured by the direct observation method.[Results] The average initial contact angle of the natural silty soil was 41.5°, which was much greater than 0. Only one of the three methods widely used for measuring the dynamic contact angle of a continuous surface solid can measure the dynamic contact angle of the surface of soil particles with a receding contact angle of three soil samples greater than 0. The initial contact angle had little influence on the change rule of the contact angle between the soil particles and pore water during the process of evaporation (dehumidification). The change rule of the contact angle between different soil particles in the dehumidification process of the same sample was not consistent, and the contact angle may even change from small to large in the dehumidification process. The humidification modes of hydrophilic and hydrophobic soil were quite different. In the humidification process, pore water first formed a liquid bridge and then formed a liquid film covering the hydrophilic soil particles, while repellent soil first formed liquid droplets on the surface of the soil particles and then connected the droplets to form a liquid film covering the soil particles.[Conclusion] The contact angle of soil particles lags significantly, and the contact angles between the soil particles and the surfaces of the soil particles are not consistent. Therefore, the contact angle must be strictly distinguished in practical applications.