Take bus 518. Searching Baidu Map shows that you can take several buses from Nantong Railway Station to Wanda Plaza and take bus No. 518. The whole journey takes 35 minutes. The specific bus route:

1. First, walk 610 meters from Nantong Railway Station Square. Nantong Railway Station 518 bus stop.

2. Next, take bus 518 from Nantong Railway Station to Wanda Plaza via stop 19.

3. Finally, walk 130 meters to reach Wanda Plaza.