The dehydrogenation of n-dodecane is industrially significant, yet Pt-Sn catalysts widely used for this reaction are often limited by poorly controlled Pt-Sn interactions and ill-defined metal chemical states. Here, a Pt-Sn/β zeolite catalyst is constructed by grafting Sn onto dealuminated β zeolite via Si–O–Sn bonds, followed by reduction-controlled Sn precipitation that drives dynamic Pt re-dispersion. X-Ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), X-Ray photoelectron spectroscopy (XPS), X-Ray absorption fine structure (XAFS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirm that this process generates well-dispersed Pt-Sn intermetallic active sites at 540 °C, with enhanced bimetallic modulation and geometric isolation. The optimized catalyst achieves a product formation rate of 0.00714 mol·g_Pt⁻¹·s⁻¹. These findings establish reduction-temperature-controlled Sn precipitation as an effective strategy for tuning Pt-Sn active sites and offer a practical design principle for efficient long-chain alkane dehydrogenation catalysts.