The shear strength and permeability of gravel layer are in general higher than those of sandy or clayey materials, and the behavior of deep excavation in gravel layer is different as a result. This paper describes three deep excavation sites located in Taipei county, which were mainly excavated within gravel layer, and the characteristics of monitoring data are discussed. These cases indicated that pressure acting on diaphragm wall and internal struts were relatively small for deep excavations in gravel layer, and the wall displacement was small as well, while the control of groundwater flow was a main issue during diaphragm wall construction and subsequent basement excavation.