The construction of high gravelly soil corewall rockfill dams on thick overburden layer has developed rapidly in recent years. At the same time getting a clear understanding and a reasonable numerical simulation method of the deformation law is an important problem. The factors that affect the deformation of rockfill dams are many-sided and complex. The measured results of deformation are very significant for the above problems. Based on the monitoring data of Yaoji dam, a 100 m level gravelly soil corewall rockfill dam on thick overburden layer, and combined with the actual construction process and reservoir impounding process, the dam deformation, gravelly soil corewall deformation are analyzed. Maoergai dam has high similarity with Yaoji dam in the height of dam, the depth of overburden, the width of valley. Comparative analysis of these two dams’ monitoring data is also conducted. Based on the analysis, some clear understanding of the deformation law of this kind of dam are obtained. The influence of wetting deformation, creep deformation, construction and impounding method is learned, so as to provide reference for modeling and predicting deformations of similar projects.