The fabrication of different perovskite materials with superior properties into lateral heterostructures can greatly improve device performance and polarization sensitivity. However, the sensitivity of perovskites to solvents and environmental factors makes the fabrication of lateral heterojunctions difficult. Here, we realize high-quality perovskite microwire crystal heterojunction arrays using regioselective ion exchange. Photodetectors with responsivity and detectivity up to 748AW-1 and 8.2×1012 Jones are fabricated. The photodetector exhibits responsivity as high as 13.5AW-1 at 0 V bias. In addition, the device exhibits ultra-high polarization sensitivity with a dichroic ratio of 5.6, and 81% of its performance was maintained after 144 days of exposure to air.