A method for preparation of iloperidone is provided which comprises reacting 6-fluoro-3-(4-piperidinyl)-1,2-benzoisoxazole hydrochloride with 1-[4-(3-chloropropoxyl)-3-methoxyphenyl]ethyl ketone in an inorganic alkaline aqueous solution. A crystallization method of iloperidone is also provided which comprises adding seed crystal to the iloperidone solution in ethyl acetate, and then iloperidone crystal is obtained with high purity by controlling the temperature and the stirring speed.
