Abstract: As a comprehensive and complex work, government investment auditing often involves reviewing the entire process of project construction, involving various stages of review and supervision before, during and after the event. In order to effectively standardize the behavior of project cost management and improve the level of cost management, it is of great significance to apply government investment auditing to project cost management. Based on this, this article analyzes and discusses the application points of government investment audit in the three stages of project cost, in order to provide a reference for the development of follow-up work.