Hong kong 18 years old to change identity cards. How to return to the mainland during this period? I don't have a re-entry permit and passport.

If you have applied for a new identity card in Hong Kong, but have not yet obtained a re-entry permit or passport, you can return to the Mainland through the following channels:

1. Apply for a temporary home visit permit: You can apply for a temporary home visit permit from the Hong Kong Immigration Bureau and use it when you return to the Mainland. Please note that the temporary home visit permit can only be used once, and it is valid for only three months, so you need to return to the mainland within the validity period.

2. Apply for a passport: You can apply for a passport from the Hong Kong Immigration Department to use when you return to the Mainland. Please note that if you already have Hong Kong permanent resident status, you need to provide relevant documents to prove your identity.

3. Use other documents: If you have other documents that can prove your identity, such as Hong Kong permanent identity card and birth certificate, you can also use these documents to return to the Mainland. Please note that these documents may need to be certified by relevant departments.

No matter which way you choose to return to the mainland, it is recommended that you consult the relevant departments or institutions in advance to ensure that you meet the relevant requirements and abide by the relevant regulations.