A novel polymeric precursor for SiC-ZrC composite ceramics was synthesized by methyl trichlorosilane, dimethyl dichlorosilane, zirconocene dichloride and sodium in one-pot synthesis. The pyrolysis behavior and structural evolution of the precursor, the microstructure and composition of the synthesized ceramics were fully investigated by TG, FTIR, XRD and SEM. The results show that the precursor can completely be transformed into SiC-ZrC composite ceramic after heat treatment in argon at temperatures above 900 ℃ with ceramic yields above 60%. The obtained ceramic consists mainly of amorphous matrix phase SiC, in which ZrC nanocrystallites are distributed uniformly with 10 to 45 nm in size. This new precursor is suitable for production of ultra-high temperature ceramic fiber and ceramic matrix composite.