I assume your question is about performing the internal audit
The main purpose for performing internal audits of your Company’s ISO 17025 management system is to check how effective the system is, by checking if the right things have been implemented and if they are adequately maintained.
The role of ISO 17025 internal auditors is to look at the laboratory’s processes (both management and technical) and check for:
conformity to ISO 17025 (where the requirements of ISO 17025 were correctly identified during implementation?)
conformity to your laboratory’s own requirements (is there evidence that the implemented processes compare to what was planned in your management system?).
Internal auditing is also a great tool to find opportunities for making improvements to processes.
The auditing process starts with auditors having a good understanding of the requirements and purpose of the ISO/IEC 17025:2017 standard (see the all-new 17025 Academy https://advisera.com/17025academy/). The next step is the planning, followed by performing the audit and producing the audit report, where you will include the list of nonconformances raised.