In order to investigate the influence of precursors on impregnation behaviors of C/SiC composites, C/SiC composites (C/SiC-0,C/SiC-Ⅰand C/SiC-Ⅱ) prepared with three different precursors (solid polycarbosilane, PCS(s)), liquid polycarbosilane PCS-Ⅰ(l) and PCS-Ⅱ(l)) were prepared via precursor infiltration and pyrolysis (PIP) method. Impregnation behaviors of different precursors were studied to mainly focuse on the combination of mechanical properties as well as microstructures of C/SiC composites with different PIP cycles. Results showed that C/SiC-Ⅰ composites exhibited the highest flexural strength of 336 MPa. The microstructures of C/SiC composites showed that the internal pores of C/SiC-0 composites were distributed between carbon fiber bundles, C/SiC-I composites were dense and the pores were evenly distributed. The pores of C/SiC-II composites were inside carbon fiber bundles and SiC matrix. Gel permeation chromatography (GPC) results showed that due to the difference of molecular weights of the impregnating solution, the macromolecules cannot impregnated into the carbon fiber bundles, which resulted in the lack of SiC matrix and degradation of mechanical properties for the composites after PIP cycles.