The present invention discloses a crystal of potassium ion competitive acid blocker and preparation method thereof. In particular, the present invention relates to a potassium ion competitive acid blocker, namely 1-[5-(2-fluorophenyl)-1-(pyridin-3-yl sulfonyl)-1H-pyrrol-3-yl]-N-methyl-methylamine fumarate (hereinafter referred to as formula I) in crystalline form and a preparation method thereof, having an X-ray powder diffraction pattern with characteristic peaks comprising 2 θ values (± 0.2 °) measured by CuKa1 radiation: 12.30, 13.59, 15.34, 18.67, 20.48, 21.69, 25.23, 26.92. Type I polymorph of the present invention is stable, reproducible and suitable for drug development.本發明涉及鉀離子競爭性酸阻滯劑，即1-[5-(2-氟苯基)-1-(吡啶-3-基磺醯基)-1H-吡咯-3-基]-N-甲基甲胺富馬酸鹽(以下簡稱式I)的晶型及其製備方法，其X射線粉末衍射特徵峰如第1圖所示。本發明所提供的式I晶型性狀穩定，可重複性好，適合藥物開發。
