According to the experience of querying Baidu, the query method of postal joint line number is as follows:

1. Open WeChat and click China Post from the official account page of WeChat.

2. Click on the postal service, and then click on the financial services.

3. Select the bank to query on the service platform.

4. Enter the queried account information, and click Query to query the correspondent bank number of this bank.

The bank line number is the unique symbol of a regional bank, which is used for cross-regional payment and settlement business such as large payment system, small payment system, bank draft system of city commercial banks and national check imaging system (including automatic bill sorting system in some cities) organized by the People's Bank of China. It consists of 12 digits: 3 digits of bank code +4 digits of city code +4 digits of bank number+1 parity bit.