Based on post-classical narratology and narrative discourse theory, this paper explores the narrative structure and creative intention of the film Nobody Knows, directed by Hirokazu Koreeda in 2004 from three aspects: narrative time sequence, image symbols and ideology. The article first introduces the development of narratology, distinguishes the difference between classical narratology and post-classical narratology, and points out that post-classical narratology expands the research scope to other media forms. Then, through a specific analysis of Nobody Knows, the implicit social and cultural criticism in the film is revealed. Finally, this paper concludes that a narrative discourse analysis of Nobody Knows helps to gain a deeper understanding of its underlying meaning and implications, providing valuable inspiration for domestic works.