Burial diagenetic alteration is an important factor for increasing or maintaining the reservoir performance in deep carbonate reservoirs. As one of the control factor, the identification of magmatic hydrothermal fluid activity is critical. Nowadays, the prediction of magmatic hydrothermal fluid activity is based on trace elements and C, O, Sr isotope and has more uncertainty, which impacted the difficulty of reservoir evaluation. So, it is imminent to look for a reliable method to predict magmatic hydrothermal fluid. As a major element in carbonate rocks, the development of Mg isotopes in recent years provide an importance new tools for this proposition. .In this proposal, we question if the Mg isotopic composition in carbonate rocks will change during the activity of magmatic hydrothermal fluid. To answer this query, we propose to investigate the Mg istop composition change in the samples of carbonate rocks and intrusive rocks of Yingshan-Yijianfang Formation, Ordorvician, Tarim basin.which located three research objectives: (1) Determining the change of Mg isotopic composition in carbonate rocks surrounding Intrusive rocks. (2) Clarifing the controlling factors for Mg isotopic variations in carbonate rocks; (3) Estabilishing the Mg isotope prediction model for magmatic hydrothermal fluids.