Hi, Jhuman Chakma,
Greetings from Sophie, Top China Travel!
Thank you very much for question about traveling to Hong Kong.
Please be advised that citizens need to apply for Hong Kong visa before they travel to Hong Kong.
Therefore, no matter how long you are working in China with China working visa, you also need to apply for a Hong Kong visa when you travel to Hong Kong. You could contact with the Exit and Entry Administration in the city where you are working to know how to apply for a visa to Hong Kong for a foreigner. I suggest you contact with the Exit and Entry Administration with the assistance from one of your Chinese friends.
Besides, when you decide to travel to Hong Kong during the period you are working in China, please check whether your China visa is a single entry or multiple entry one. If single entry visa, you may not be allowed to enter mainland China again after traveling to Hong Kong, unless you apply for a new visa.
Hope the above is clear and helpful.
Sophie Huang
Top China Travel