Using methyldichlorosilane with 1-dodecene as materials have successfully synthesized dodecylmethyldimethoxysilane using self-made platinum catalyst, and then dodecylmethyldimethoxysilane was synthesised via alcoholysis reaction through atmospheric liquid-phase reaction. The structure of target compound was characterized by means of 1HNMR and IR spectrum. The reaction conditions have been optimized as follows: feeding speed of dodecene 5mL/min, n(methyldichlorosilane)∶n(1-dodecene)=1.1∶1, m(platinum catalyst)∶m(methyldichlorosilane) = 1.5×10﹣4∶1, reaction temperature 110℃, reaction time 20min and the yield of intermediate product could reached 92.5%, selectivity to β-addition product was 100%. Feeding speed of intermediate product 1mL/min, methanol steam flow 1500mL/min, eaction temperature 85℃, the purity of the dodecylmethyldimethoxysilane was 97% after the separation and purification processes，the yield of product could reached 90.5% .