Abstract: The ejector mixer plays a decisive role in the cooling and noise reduction of gas turbine. Compared with the traditional ejector mixer, the ejector mixer with valve plate structure has better performance. In order to fully explore its internal flow characteristics and provide a basis for optimal design, the computational fluid dynamics (CFD) numerical simulation was used to study the ejector configuration with or without valve plate. The ejector performance parameters such as ejector ratio, average outlet temperature, maximum temperature and average outlet velocity were compared and analyzed. The ejector performance with different valve openings was analyzed for the ejector mixer with valve plates. The results show that the mixing performance of the ejector mixer with valve plate structure is significantly improved. The ejection performance is the best when the valve opening is 45°.