Various levels of calculations are applied to obtain the structures, energies, dipole moments, vibrational spectra, rotational constants, and isomerization of SiC3P species. A total of 27 minima which are connected by 40 interconversion transition states on the potential energy surface are located at the DFT/B3LYP/6-311G(d) level. The global minimum is found to be a linear SiCCCP of the (2)Pi electronic state. Besides the three-membered-ring isomer CC-cCPSi (36.2 kcal/mol), the four-membered-ring isomers P-cCCCSi (31.2 kcal/ mol) and P-cSiCCC (79.1 kcal/mol), the five-membered-ring isomer cCPCCSi (46.6 kcal/mol), and the cagelike isomer pPSiCCC (56.8 kcal/mol) also possess great kinetic stability (more than 10.0 kcal/mol). The bonding natures of the relevant species are analyzed. The calculated results may be helpful for understanding the P-doped SiC vaporization process. The structures, energies, and bonding properties of the relevant species are compared with those of the SiC2N, SiC2P, and SiC3N analogues.