Currently, there’s no process of importing transactions from Mint.com directly to QuickBooks Online (QBO), nor can it export information from QBO to Mint. If its all bank transactions, then you may be able to export from Mint as a CSV (comma-separated values) file. But it’s the same thing as importing directly from your bank account.
When you first connect your account, QuickBooks typically downloads up to the last 90 days of transactions.
You can import the bank feed prior to 90 days (or for missing transactions) using the following two methods:
1) Web Connect (QBO format):
https://community.intuit.com/articles/1145233-upload-more-than-90-days-of-bank-transactions-through-web-connect
(Some banks offer to download QBO format. You will need to check with your bank).
2) Excel (CSV format):
https://community.intuit.com/articles/1458636-import-bank-transactions-from-excel-csv-file-to-quickbooks-online
