Synthetic reactions with distinctive physicochemical properties and the study of functional groups during synthesis provide an effective way to design polymers on an individual basis. The functionalization of polymethylhydrosiloxane (PMHS) has been performed via hydrosilylation of PMHS with selected alkenes with different active functional groups. In the reaction of PMHS with selected CC bond‐containing olefins in solvent‐free systems, the most efficient catalyst system can be selected to obtain the PMHS reagents to introduce the desired functional groups while generating only regional isomeric products. On‐line real‐time monitoring techniques, in situ Fourier‐transform infrared (FT‐IR), were utilized to determine the chemical reaction rates and reaction conversions for each chemical reaction, and to assess the merits of the reaction systems. In addition, the structures of the functionalized polymers were characterized using FT‐IR spectroscopy, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). The kinetic parameters of typical chemical reaction processes were calculated using Kissinger's equation and Ozawa's equation. The comparisons between solvent and solvent‐free systems were carried out under the same conditions, and the statistics revealed that the solvent‐free system was more efficient than its solvent‐based counterpart. This research on the introduction of monofunctional groups into PMHS side chains might pave the way for a variety of diverse functional groups, thus allowing for the further application of PMHS and its derivatives.