Hybrid methylammonium lead tribromide (MAPbBr) perovskite has attracted great attention in ionization radiation detection. However, the charge collection remains a challenge. Here, fast response and high-sensitivity X-ray detection based on MAPbBr single crystals with a surface barrier Schottky diode has been achieved at room temperature. The Schottky surface barrier can overcome the large leakage current at a high electrical field, enabling us to reduce the noise and increase the charge collection efficiency. This surface barrier device has been demonstrated a 3 times improvement over the photoconductor based X-ray detector, which enables usage in nuclear medicine, especially for X-ray imaging technology.