Three diversiform microstructures of silicon carbide (SiC) including powder (SiCp), whisker (SiCw), and nanofiber (SiCn) were used as supports to stabilize stearic acid (SA) for preparing composite phase change materials (PCMs). The SA/SiCp, SA/SiCw, and SA/SiCn4 composites were obtained by vacuum impregnation and SA/SiCn1, SA/SiCn2, and SA/SiCn3 were synthesized by ethanol method. The thermogravimetric analysis indicated that the loadages of SA were 7.18% and 56.74% for SA/SiCp and SA/SiCw, and the loadages of SA were 28.11%, 46.53%, 66.91%, and 81.66% for SA/SiCn1, SA/SiCn2, SA/SiCn3, and SA/SiCn4, respectively. The thermal conductivities of composites were 61.80-169.29% higher than the pure SA. The results of Fouriertransform infrared spectroscopy and X-ray diffraction analysis indicated that there was no chemical reaction between supports and SA. The composite PCMs had good structural stability and chemical stability. The SA/SiCn4 had the best comprehensive performance in the thermal energy storage and release process due to its higher thermal conductivity and thermal storage capacity. The thermal infrared images suggested that SA/SiCn4 was more sensitive to temperature changes. Furthermore, thermal management testing presented that SA/SiCn4 had a good performance for the thermal management of lithium-ion batteries.