The rapid development of artificial intelligence content generation (AIGC) technology is profoundly changing the production mechanism and Aesthetic Logic of cultural and tourism promotional films. In traditional films, grassland is often shaped as an "epic space" carrying the depth of history and cultural identity; However, with the short video becoming the mainstream communication form, the grassland culture and tourism publicity has shown a trend of lightweight, instant and interactive. This study takes the AIGC generated culture and tourism publicity video officially released by the Department of culture and tourism of Inner Mongolia Autonomous Region as the sample, and uses the qualitative text analysis method to systematically investigate the Reconstruction Path of grassland audio-visual language from the three levels of formal structure, symbolic meaning and narrative construction. The study found that AIGC technology promoted the transformation of grassland video from "epic space" to "ecological paradise": in form, it was shown as space-time compression and scene collage, in symbol, it was shown as visual animation and auditory affinity, and in narrative, it turned to modular display and interactive call. This transformation is not a simple technological substitution, but a cultural adjustment under the joint action of technological characteristics, platform logic and communication needs. The research reveals the remodeling mechanism of grassland image in digital communication ecology, and also provides a new perspective for understanding how technology participates in the construction of images of localness.