The invention discloses an 
expansive-soil slope hygroscopic deformation model experiment method and a 
system. The 
expansive-soil slope hygroscopic deformation model experiment method comprises following steps: A, soil samples are turned and subjected to sun 
drying so as to control 
water content and soil filling thickness; B, soil filling is carried out by 
layers, slope 
cutting is carried out uniformly, and a part of monitoring components are buried; C, an obtained soil slope is allowed to stand until cracks are generated, and a displacement sensor is arranged; D, 
physical quantity initial values are recorded; E, a 
rainfall simulator is used for realizing dropping-pouring type concentrated rainfall, and rainfall amount is controlled; F, physical quantities and rainfall amount are monitored according to rainfall stages; G, a rainfall-
evaporation cycle is carried out repeatedly so as to stimulate 
drying and watering cycle; and H, slope 
morphologic change is recorded, and results are analyzed. The 
system comprises a model case, monitoring components, and a 
rainfall simulator; the monitoring components are arranged in the model case; and the 
rainfall simulator is arranged on the upper part slope shoulder of the model case. The 
expansive-soil slope hygroscopic deformation model experiment method and the 
system are suitable for a plurality of expansive-soil slope hygroscopic deformation model experiments, and possess significant importance for researches on expansive-soil 
slope stability and catastrophe mechanisms.