Abstract: The purpose of this study was to produce ultrafine sumatriptan succinate (SS) for dry powder inhalation formulation via reactive crystallization. The effects of mole ratio of sumatriptan to succinic acid，reaction temperature and mixing intensity on particle size and morphology were investigated. Fourier transform infrared spectroscopy，scanning electron microscopy and X-ray diffraction were used to characterize the physicochemical properties of as-prepared SS dry powder. The results showed that ultrafine particles of SS with an average size of about 1μm could be produced and well controlled under the following conditions，mole ratio (nST∶nsuccinic acid) 1∶2，at 0—15 ℃，mixing intensity 10000r/min. Furthermore，after foundational aerosol performance evaluation，the fine particle fraction (FPF) (<5μm) was increased up to 25.35%，which was approximate 5 times of the FPF value for the milled commercial SS.