The invention belongs to the field of organosilicone material synthesis technology and specifically relates to a preparation method of an organosilicone monomer. The preparation method comprises the following steps: adding an organic solvent and an alkoxyl-substituted organosilicon oligomer into a reaction kettle, pouring organic strong base, introducing inert gas, stirring and mixing uniformly, stirring and reacting, dropwise adding halogenated hydrocarbon into the reaction kettle and balancing after dropwise addition; or adding an organic solvent and organic strong base into the reaction kettle, introducing inert gas, stirring and mixing uniformly, adding halogenated hydrocarbon, stirring uniformly, dropwise adding an alkoxyl-substituted organosilicon oligomer, and balancing after dropwise addition; filtering a balanced reaction solution, and separating a reaction product and an organic solvent after distillation of a filtrate. The reaction condition is mild; operation is simple andfeasible; the raw materials are cheap and easily available; safety is high and yield is high; and the preparation method is easy for industrialization.