If you plan to bring your helper with you to China for a trip, the helper needs to apply for a tourist visa. Check the requirements of domestic helpers in Hong Kong apply for visa for tourism here. If you are in Singapore, you can submit the tourist visa application at Chinese Visa Application Service Centre.
Hire a domestic helper to work in China is prohibited in most parts of the country. Currently, only expats in Guangdong province including Hong Kong and Macau residents can apply for a work visa for their domestic helpers. Chinese nationals are not allowed to hire a helper to work in the country.