Layered FeSe has become one important superconducting material, but the major challenge in the growth of large crystal makes it difficult to further clarify the underlying superconducting mechanism. In this research, large crystals with a typical size of 7×2×2 mm3 are obtained simply by using KCl flux with a controlled temperature gradient inside the flux. Superconducting tetragonal β-FeSe phase with the basal plane of (101) face is identified by X-ray diffraction analysis. The super large crystals show outstanding superconducting performance with transition happened at 9 K according to the DC magnetization measurements and broad resistive transition to zero resistance at 10 K with an onset temperature of 15 K. Our work has provided a convenient method to synthesis large FeSe single crystals which is promising in investigations of FeSe-based superconductors.