Dear Poonam Patil,
Greetings from Sophie, Top China Travel!
Thank you very much for your question.
At first, since your are studing in China, then you have China visa. In this case, there isn't any problem for you to travel to Guangzhou from any of cities in mainland China.
Secondly, Indians are allowed to visit Hong Kong within 14 days without visa. Therefore, if you visit to Hong Kong and stay there within 14 days or transit flight in Hong Kong airport, you will not need any Hong Kong visa, but you need to hold your departing Hong Kong air tickets. If your air ticket is e-ticket, then you need to print the confirmed e-ticket before you get on the train or bus from Guangzhou to Hong Kong.