Abstract: After reexamining the horizon producing the Dashankou Fauna and the division of Permo-Triassic strata in northern Qianlian area, China, we found the misuse of the name “Xidagou Formation”. Xidagou is held as group name for lower-middle Triassic of northern Qilian area, and cannot apply to other strata. We suggest rename former Xidagou Formation with Dashankou Fauna as Qingtoushan Formation and design the Qingtoushan section as the holostratotype; and the former Xidagou Formation applied to upper Triassic should be renamed.