Volunteers recruited online also performed traditional Tang dances on the platform at Anyuanmen Station, one of the line's busiest stations.
Within two hours of the initial journey, short videos of the train had topped 5 million clicks on video-sharing app Douyin, with more than double that across all online platforms.
The period decorations were created by artists under the guidance of experts from Northwest University in Xi'an, said Chen Hongchao, office director of Xi'an Metro Co.
"Nowadays, many people - especially younger generations - are obsessed with mobile phones and computer games," Chen said.
"We hope to promote awareness of Xi'an's traditional culture and Tang poetry through this campaign."
Xi'an is one of the "four great ancient capitals of China", along with Beijing, Nanjing and Luoyang.
"The special train is expected to run through the end of this year. We are planning to launch more decorated subway cars if this one is well received by citizens," Chen said.
Back in September 2015, the Xi'an Metro gave one of its subway cars a makeover on the International Day of Peace. This helped revive stories of the ancient Silk Road amid the urban hustle and bustle of daily subway commutes.
A few cities in China have recently transformed interior designs of subway cars as part of publicity efforts to enhance cultural awareness.
For example, Chengdu, Sichuan province, launched a book-themed train in April that narrated the evolution of the forms of books in China - from ancient bone carvings to modern methods of enjoying the written word.
Wang Xiaoyu contributed to this story.
