T The "Y" field of the "X" layer is located in Jambi Province which was discovered in October 1928 with an OOIP of 269 MMSTB, a recovery factor of 33.46%. The "X" layer of the "Y" field experienced a decrease in reservoir pressure resulting in a decrease in oil production. In April 1995 the waterflooding project began. The purpose of this study was to determine whether the waterflooding performance was optimum or not. The method used in this study includes several analyzes, namely drive mechanism, connectivity, Hall plot, Chan diagnostics, voidage replacement ratio, bubble map, and additional recovery factor. The determination of drive mechanism using the method of Ganesh Thakur and MBAL software found that the "X" layer has the driving force of the solution gas drive. In the analysis of response connectivity between injection and production wells, most of them have poor responses. In Chan’s diagnostics analysis, most of the production wells experience rapid channeling problems. In the Hall plot analysis most injection wells experience positive skin problems. In the voidage replacement ratio analysis, the results are unfavorable because the cumulative value is still below 1, 0.51. In the Scatter plot analysis, it was found that 25 production wells had a high watercut value so that they could be candidates for injection wells. In the bubble map analysis, the largest production was obtained in well Z-005. Recovery factor after injection was obtained 36%. The results obtained from the above analysis that the performance of waterflooding is not yet optimum.