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. XRD, HRTEM, XPS, XAFS and in situ 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.