The ejector system is used for making a vacuum in an enclosed tank. This research represents the method to improve ejector performance by inserting a strut at the center of ejector outlet. This proposed ejector system is so simple and have a low cost to improve the ejector performance. There are many kinds of method for obtaining a lower vacuum pressure. The ejector is consists of nozzle, straight pipe and outlet diffuser and we focused on the outlet diffuser for high ejector performance. The strut is located at the center of ejector outlet diffuser. As the experimental result, we compared the vacuum pressure with and without a strut and without strut, and the ejector performance showed an improvement with 40% or more than the case without strut. This means that the stable fluid low energy loss was obtained by inserting the strut.