The friendly was delayed for 25 minutes before fans agreed to put the flag away, resulting in the Chinese side returning to the pitch.
China's U20s first game in Germany (vs. Schott Mainz) has been interrupted.
Tibetan fans in the crowd have unveiled their flag.
The Chinese players have refused to play on.
(via @PaulBartmuss + )#ChinaU20 pic.twitter.com/NTYMI78sjT— DW Sports (@dw_sports) November 18, 2017
The China U-20 team was controversially included in the fouth-tier Regionalliga Sudwest this season after just 19 teams qualified for the league.
Needing to fill up the teams' fixture list, the side was added as part of a five-year agreement between Germany and China with the aim of improving Chinese youth football.
Three of the league's 19 teams have refused to take part in the arrangement, with the other 16 teams set to face the Chinese youth side in a friendly during the second half of the season.
But the first match has already proved controversial, as many continue to push for Tibetan independence from China.