What documents do Italian immigrants need to get married with Hong Kong people? Do they need a visa for the first time?

My situation is similar to yours. I have been in Italy for eleven years. I have a China passport, but my China account is gone, and my girlfriend is in China. The procedure for getting married is:

First, you go to the Consulate of China in Milan to apply for the single certificate/unmarried certificate, and then take this certificate and your passport back to the civil affairs bureau where BF is located, and ask him to bring his household registration book and ID card in China.

If you need anything else, the local civil affairs bureau will tell you, but what is missing is only your BF's things. You just need to bring your unmarried certificate and passport from Milan consulate.