Currently, there is no direct train running between Yongkang and Zhongshan. And, the Zhongshan City doesn't has railway until now. So, I think you have to transfer at Guangzhou City. Firstly, please take the train K328/K325 (20:53~the next 15:44)from Yongkang to Guangzhou Railway Station. The train fare is about 330RMB for a hard sleeper. To the west of the railway station, there is the Guangdong Province Bus Station, where frequent buses departing to Zhongshan City from 06:30 to 21:30 everyday. The journey is just 1.5 hours and 46RMB.

Around the city center at Wangchun Rd and Jincheng Rd, you could find many hotels. Very easy to lodge in when you arrive there~