It turned out that the husband and wife got married in the mainland, and later the woman immigrated to Hong Kong and the two sides divorced. Can they remarry after two years?

Remarriage has nothing to do with time

"After divorce, if both men and women voluntarily resume the relationship between husband and wife, they should go to the marriage registration office to register for remarriage." According to Article 8 of the Registration Method of Marriage Law, both parties must apply for remarriage in person at the marriage registration office where one party's household registration is located, and must also issue a divorce certificate or a court judgment (or mediation). After the examination of the marriage registration office, the marriage certificate will be issued and the divorce certificate or divorce legal documents will be withdrawn. In this way, the legal relationship between husband and wife is restored and protected by law. If you live together without remarriage registration, you can neither obtain legal marital status nor get legal protection.