Abstract: The documentary Masters in the Forbidden City is the sole large-scale documentary so far that systematically shoots the story of the restoration of rare cultural relics in the Forbidden City. It records the daily life of cultural relics restorers with plain lens. The film, with subtitles in both Chinese and English, has expanded its audience at home and abroad. By analyzing the subtitle translation of the documentary from the perspective of eco-translatology, it can be found that, after adapting to the specific translation ecological environment of the documentary, the translator completes the adaptive transformation in language dimension, culture dimension and communication dimension to achieve a high degree of harmony. Eventually, the effect of promoting the spirit of craftsmen and spreading traditional Chinese culture is achieved.