Embodiment of present disclosure provides a method for preparing ceritinib of formula I, comprising: (1) contacting a compound of formula 12b with an amino protective group to obtain a compound of formula 3; (2) contacting the compound of formula 3 with a compound of formula 9a to obtain a compound of formula 5; and (3) subjecting the compound of formula 5 to a deprotection reaction to obtain the ceritinib of formula I. Then ceritinib may be effectively prepared.