In the movie "Empress Wu Zetian," Li Yu plays the role of Empress Wu Zetian wearing a green long skirt, which is one of the court costumes of the Tang Dynasty.

The Tang Dynasty was a prosperous and flourishing dynasty in Chinese history, and green was the exclusive color of the Tang imperial family.

This green long skirt not only showcases the beauty and elegance of the Tang court costumes but also reflects the Tang imperial family's admiration for nature and life.

In addition, this green long skirt has certain symbolic meanings, representing Empress Wu Zetian's power and status.

Through this green long skirt, audiences can better understand the Tang court culture and historical background.