which subway lin should we use to reach xi'an mainhua aparthotel from main railway station?

First, you need to walk about 900 meters southwards along Jiefang Road to Wulukou Metro Station. Then you can take metro line 1 to Beidajie Station and transfer line 2 to Nanshaomen Station, Exit D. Afterwards, you may walk 50 meters ahead along North Chang’an Road and turn right to East Youyi Road for about 150 meters. Then you may turn right for 140 meters to find your hotel.
From your hotel to Terra-cotta Warriors, you need to go back to the Main Railway Station first. Afterwards, you can take tourist bus line 5 to the scenic area directly.