As for the situation you mentioned that "the credit line of 400,000 yuan from China Construction Bank is about to expire", it means that the 400,000 credit line you obtained is about to expire. This means that you can use this 400,000 limit for loans or credit card purchases within a certain period of time. After expiration, you will no longer be able to use this part of the quota.

It is worth noting that China Construction Bank will generally notify you of the expiration date of the credit line in advance so that you can make corresponding arrangements for repayment or use. It is recommended that you pay attention to the bank's notices and account information in a timely manner to ensure that you understand the expiration time and related requirements of the credit line.

In addition, the "online loan big data" you mentioned refers to a third-party credit inquiry system provided for lending institutions. It can integrate loan records from various online lending platforms to help lending institutions understand the borrower's credit status more comprehensively and accurately. By using this system, lending institutions can identify problems with their online lending big data and take appropriate measures to resolve them.