Precursor polymers to manufacture Si-C-O fibers are prepared by thermal rearrangement reaction of Polyvinylchloride(PVC) and Polydimethylsilane.The precursor polymers are characterized by element analysis and IR.Test results show that the copolymer —(SiCH3H—CH2 )n—( CH＝CH).m— is obtained when high PVC content is added to reactive system.The Si-C-O fibers with low resistivity of 100 Ω·cm are obtained through melt spinning,infusibi-lization and heat treatment of the precusors at high temperature,while SiC fibers with high resistivity of 106Ω·cm may beobtained by polycarbosilanes.