The invention discloses a method of silicon removal pretreatment of molten iron, belonging to the technical field of pretreatment of the molten iron. The method comprises the following steps of: preparing a silicon removal agent used for pretreatment of the molten iron, when reladling and tapping through a torpedo ladle, adding the silicon removal agent along with iron stream so as to remove the silicon, wherein the additive amount is decided according to the mass percentage composition of the initial silicon of the molten iron and the mass percentage composition of the target silicon; after tapping, blowing nitrogen into an iron ladle by utilizing a molten iron desulphurization device and stirring for 3-5 minutes, if the molten iron requires sulfur removal, carrying out jetting and light sulfur removal treatment, and carrying out slagging operation lastly. The method, provided by the invention, has the advantages that the silicon in the molten iron is effectively removed, and the silicon removal rate is up to 50%.