Audit bureau is an administrative unit, so it can't learn much knowledge.
It is suggested to spend a few years in China Railway or China Construction to get familiar with the basic practical knowledge of cost, and then go to a cost consulting agency, which will greatly increase your knowledge. The agency mainly focuses on auditing, and all kinds of projects are available. You can also learn from the experience of other professionals, and you can greatly improve your professional level by dealing with different levels of cost professionals. After this, it's up to you. Finance Bureau and Audit Bureau often recruit professionals for the society. Going directly to the audit office has little future, no education, no experience, just a small clerk, and will never succeed.