The invention discloses a method for synthesizing phenyl-containing organosilicon monomers. The method comprises the steps of performing one-step Grignard reaction on raw materials including methyltrimethoxy silane, magnesium and benzene halide: performing activation initiation reaction in the presence of a catalytic initiator under the condition that a solvent is added or not added, heating, continuously reacting, filtering and distilling to obtain methyl phenyl dimethoxy silane and methyl diphenyl methoxy silane. According to the method, the novel and cheap raw materials including methyltrimethoxy silane, magnesium and chlorobenzene (or bromobenzene) are used, and the raw materials react at a certain temperature by adopting the one-step Grignard method and using iodine as the catalytic initiator, are heated and then continuously react to obtain methyl phenyl dimethoxy silane and methyl diphenyl methoxy silane, thus solving the problem that the preparation of methyl phenyl dimethoxy silane with the one-step Grignard method is not realized at present and the problems of low yield, high production cost and the like when methyl triethoxysilane is used as a raw material, and meeting the requirements of modernized industrial production for high yield and low energy consumption.