Height difference between the crown and the toe of rupture surface of Zhaizicun landslide along the right bank of Jinsha River is 638 m, with about 2.5×108m3 total rock displaced. The giant rock landslide complex caused serious landslidedamming and the crest of the residual landslide dam with a volume of 180×104m3 on the left bank is 118 m above the river. Deposits of the landslidedammed lake with a average width of 2.6 km stretch 46 km along Jinsha Rive and the outcrop boundary takes on a branchy structure. The lacustrine deposits between 1180~1500 m above sea level consist of horizontally laminated clay and silt and sandwich fluvial sand—gravel layers. Finesandy, ripple crosslaminated and crossstratified beds show the existence of bottom currents in the landslidedammed lake. Deposits of Zhaizicun landslidedammed lake is a representative case of the Xigeda Formation. Deposits of landslidedammed lakes compose >80% of the Xigeda Formation and landslide dammed lake genesis model for the Xigeda Formation may reasonably explain various its plane outcrop shapes, profile features, the genesis relationship between the Xigeda Formation and fluvial gravel beds, highly dependence on rivers, dimension difference and space discontinuity among different regions.