Objective To prepare silicon carbide ceramic with excellent properties by precursor infiltration pyrolysis. Methods Using polycarbosilane containing beryllium and xylene as the precursor mixed slurry, SiC foam ceramic was prepared through processes of sizing and sintering with the polyurethane foam as a template. The influence of the impregnation concentration, sintering temperature and Be elements on the structure, electromagnetic properties and thermal conductivity was studied by XRD, SEM, waveguide method and guarded hot plate method. Results The amorphous SiC foam ceramic was formed after pyrolysis of PbeCS with a porosity and pore size of 70%~90% and 0.5~1.2 mm respectively. With the increase of temperature and concentration of impregnation liquid, the surface smoothness and densification of SiC would increase. The Be elements improved the ceramic production. However, the lower content of Be in preceramic polymer and high porosity resulted in that performances like low dielectric loss and high thermal conductivity were not reflected in the overall composite performance. Conclusion The SiC foam ceramic with required structure and property can be obtained by changing the impregnation liquid concentration and sintering temperature. The performance improvement by Be elements needs to be further studied.