A preparation method of functional silanes comprises: substance A and substance B are added in a three-necked bottle and a certain amount of solvent is added; the resultant mixture is stirred for 0.5-24 h in the presence of catalyst under an atmosphere of argon, resulting in the crude product; after removing the remaining solvent and catalyst, the residual product is purified by chromatographic column to obtain functional silanes; the substance A is an alkene-containing silane and the substance B is an alcohol; functional silanes with various structures can be prepared, and their structures can be controlled by regulating the ratio of substance A and substance B, thereby providing ideas for the preparation of different silanes and the structural design of silane coupling agents.