What is best way to go to Yuejiang Tower using Nanjing metro?

Sorry to tell you no subway is available, instead, you can take Bus 10/12/21/54 to Xingzhongmen. And then walk west along Jiangning Rd for 3 minutes to your destination.

Hi Anron,

Thank you! where can find those buses? is it in Xinjiekou or Xuanwumen?

If you are staying in Xinjiekou, you can take the subway line 2 to Hanzhongmen first, and then leave from Exit2. Walk waest for 3 minutes to Huju Rd, Hanzhongmen Bus Station, where you can take Bus 221.
If you are staying in Xuanwumen, take Subway line 1 to Railway Station and leave from Exit 1. Then walk north along Longpan Rd for 8 minutes to Longpan Rd, NJ Station West Bus Stop to take Bus 10.
Have a nice trip!