the use of polymethylsilane(PMS) as a ceramic precursor had a disadvantage of the lower pyrolytic yield, when the PMS transfer to SIC ceramics. The reason is the higher volatilization of PMS during the pyrolysis due to the lower molecular weight of that prepared by using the general methods. In this study, therefore, we tried to prepare the relatively higher molecular weight PMS by the variation of the mixing ratio of THF and n-hexane as a solvent and by using of the various catalysts in dehydrocoupling reaction of PMS. As the result, the higher molecular weight of PMS was obtained with the increase of the mixing ratio of THF. The use of catalysts in dehydrocoupling reaction of PMS was also increased the molecular weight of PMS. The most effective catalyst was a TiCP₂Cl₂/Red-Al, and the use of the catalyst was increased about the three times in molecular weight and the twice in pyrolytic yield of PMS.