This article is a comparative study of the differences in cognition and expression of ethnic boundaries in three representative Chinese minority writers and directors who write and make film works in Mandarin. When Chinese minority writers compose their work in both their mother tongues and standard Chinese as an official language, it has the characteristic of transcultural writing, crossing their ethnic social boundary into dominant Han. However, the differences in their literary expressions are still very significant. There are three different cognitive experiences in the writers’ works about ethnic boundaries: First, the unified geographical and linguistic–social boundary still exists. The second aspect is linguistic–social boundary crossing within geographical boundaries. The last one is the double boundary crossing between the geographical boundary and the linguistic–social boundary of the ethnic group.