According to the present invention, a catalyst composition for use in cracking hydrocarbon can be prepared by spray drying an aqueous slurry containing a flash calcined alumina obtained by contacting an aluminum hydroxide with a hot air of 350.degree.-700.degree. C. in a short time within 5 seconds, kaolin, a precursor substance of a silica-system matrix and a crystalline aluminosilicate. Since this catalyst composition contains the flash calcined alumina and kaolin in addition to the siliceous matrix and the crystalline aluminosilicate, it can exhibit an excellent selectivity for production of intermediate fractions such as kerosene, gas oil and the like, when used for catalytic cracking of hydrocarbon.