If you bought a second-hand PS4 from Hong Kong and plan to bring it back to the mainland, the following is the general active customs declaration process:

1. Check the relevant regulations: Before planning to bring a second-hand PS4 back to the mainland, first understand the customs regulations and regulations of the target country (Chinese mainland), including tariffs, restrictions on items and customs declaration requirements. You can check the official website of China Customs or consult the local customs-related agencies.

2. Cross-border e-commerce customs declaration: Under normal circumstances, second-hand items carried by individuals need to be declared at the time of entry. There is a set of cross-border e-commerce customs declaration system in the mainland. The specific operation can be inquired and declared on the relevant website of China Customs, or the corresponding customs declaration platform can be used for customs declaration.

3. Prepare relevant documents: According to customs regulations, prepare necessary documents, such as passports, purchase invoices, relevant certificates and proof of value of second-hand items, etc. Please note that customs may need to verify the true value of the declared items and the way to buy them.

4. Pay customs duties and fees: According to customs regulations, you may need to pay corresponding customs duties and other fees. The tariff fees will be calculated based on the value and tax rate of the items, ensuring that you have enough funds to pay these fees.

5. Customs Inspection and Approval: At the time of entry, you need to bring the goods you are carrying through customs inspection and submit the relevant documents to the customs officer for review and approval.

Please note in particular that the above steps are for reference only and cannot be guaranteed to be applicable in all cases. The specific operation and customs declaration requirements may vary depending on the region and timing. It is recommended to consult the local customs agency or professional customs declaration agent when carrying second-hand goods across the border for accurate guidance and advice.