<p>Against the backdrop of the international communication paradigm shifting from macro-level "national image" broadcasting to micro-level "individual emotional" narratives, how cross-cultural documentary films overcome cultural heterogeneity, deconstruct stereotypes of the "Other," and achieve intersubjective emotional resonance has become a core proposition requiring urgent attention. This study introduces Vygotsky's sociocultural theory, conceptualizing the "mother–child narrative" in documentary films as a "semiotic intervention" mechanism in cross-cultural communication. Using a constructivist grounded theory approach, we conducted a systematic three-level coding of first-person commentaries from 155 short documentaries produced under the "Looking China Youth Film Project." The findings indicate that the "mother and child" dyad, as a universal higher psychological symbol transcending racial and cultural barriers, plays a critical "semiotic mediating" role in the cross-cultural cognitive construction of foreign youth. Through coding analysis, three dimensions of semiotic intervention via maternal imagery were extracted: semiotic mediation for cultural transmission, emotional acculturation for empowering healing, and empathetic mirroring for psychological internalization. This research clarifies the cognitive reconstruction pathway of foreign youth from "gazing at the Other" to "intersubjectivity," revealing the underlying logic that "shared emotion" surpasses "cultural spectacle" in the international dissemination of Chinese stories. Furthermore, it provides empirical support for seeking the greatest common denominator of human emotions and achieving cross-cultural identity and mutual appreciation in a globalized context.</p>