Formamidinium lead iodide (FAPbI) perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product (µτ), making it as a highly promising candidate for X-ray detection application. However, the presence of larger FA cation induces to an expansion of the Pb-I octahedral framework, which unfortunately affects both the stability and charge carrier mobility of the corresponding devices. To address this challenge, we develop a novel low-dimensional (HtrzT)PbI perovskite featuring a conjugated organic cation (1H-1,2,4-Triazole-3-thiol, HtrzT) which matches well with the α-FAPbI lattices in two-dimensional plane. Benefiting from the matched lattice between (HtrzT)PbI and α-FAPbI, the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of the α-FAPbI crystal lattice. The X-ray detector based on (HtrzT)PbI(1.0)/FAPbI device achieves a remarkable sensitivity up to 1.83 × 10 μC Gy cm, along with a low detection limit of 27.6 nGy s, attributed to the release of residual stress, and the enhancement in carrier mobility-lifetime product. Furthermore, the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17 × 10 chest imaging doses.