A self-crosslinkable liquid highly branched polycarbosilane (LHBPCS) with 5.07% vinyl group and a C/Si ratio of 1.33 was used as the precursor to prepare SiC ceramic material. Microwave heating technique and conventional heating method were applied for the heating treatment process. It was found that, compared with conventional heating method, microwave heating technique could enhance the crystallinity of SiC ceramic material with small grain size at much lower curing temperature and within shorter time. In addition, the SiO2 additive could lead to less α-SiC and excess carbon, but worsen the crystallinity of β-SiC in the final samples.