Abstract: A series of MgAPO-5 molecular sieves with a wide range of Mg/P mol ratios in the gel was synthesized by a hydrothermal process.Using MgAPO-5 as acidic supports, the bifunctional NiW/MgAPO-5 catalysts were prepared by impregnation method, and applied to the hydrocracking of tetralin to produce BTEX.The synthesized MgAPO-5 molecular sieves and NiW/MgAPO-5 samples were characterized by XRD, N₂ adsorption, SEM, NH₃-TPD, Py-FTIR and H₂-TPR.The results exhibit that the Mg/P mol ratio has a great influence on the unit cell parameters, morphology, the Mg content and the acidity of MgAPO-5 samples, and the ion of Mg²⁺ is incorporated into the framework.In the hydrocracking of tetralin, with the same amount of NiW, the activity of NiW/MgAPO-5 is primarily controlled by the acidic strength of MgAPO-5.The selectivity of BTEX was determined by the combined effect of the acidity of MgAPO-5 and the (de) hydrogenation function of NiW.The highest conversion is achieved with the Mg/P mol ratio of 0.05, and the best BTEX selectivity is obtained with the Mg/P mol ratio of 0.03.