After the listed company's financial report is audited by the firm, does the internal audit still have to do internal audit on the financial report?

It depends on the purpose of doing things. If it is purely the audit of financial statements, basically the results of firm audit (external audit) should meet the requirements.

If it is other types of audit, such as internal control audit, outgoing audit or other special audit, then external audit can also be invited to participate in the implementation. However, if the internal audit departments of large and medium-sized enterprises are relatively perfect, most of them are led by themselves, and some conclusions will draw on the results of external audit.