Collapsibility is a major cause of structural damage in loess regions. Investigating the collapsible deformation of loess under varying degrees of humidification can offer more effective guidance for engineering practice. In this study, Ili loess from Xinjiang was selected as the research subject, and indoor compression tests along with other methods were used to analyze the effects of water content, dry density, and depth on the collapsible deformation characteristics of Ili loess. Humidification collapse tests were also conducted to examine the humidification deformation behavior of loess at different humidification levels, as well as the relationship between the humidification collapse amount and saturated collapse during the humidification process. The results indicate the following: (1) The collapsibility coefficient of Ili loess is linearly and inversely proportional to dry density and varies nonlinearly with water content. (2) An expression for the humidification deformation coefficient calculated from the humidification level fits the collapsibility coefficient curve well, and the curve reflects the actual decrease in the collapsibility coefficient with increasing overburden pressure. (3) The relationship curve between the humidification level and the ratio of humidification collapse to saturated collapse approximately follows a power function, which effectively captures the variation of humidification deformation of the soil with water content. These findings provide a reference for loess engineering construction and research in Ili and other regions.