The structures and isomerization Of SiC2P species are explored at various levels. Thirteen minima are located connected by 19 interconversion transition states. At the CCSD(T)/6-311+G(2df)//QCISD/6-311G(d)+ZPVE level, the lowest energy isomer is a linear form SiCCP 1 whose structure mainly resonates between \Si=C=C=P\. and \Si=C.-Cequivalent toP\ with the former bearing somewhat more weight. The second and third low-lying isomers are cyclic cSiCCP 5 (with Si-C cross-bonding) at just 3.2 kcal/mol and cSiCPC 7 (with C-C cross-bonding) at 10.4 kcal/mol, respectively. All the three isomers 1, 5, and 7 possess considerable kinetic stability either toward isomerization or dissociation, and thus are expected to be observable. The calculated results are compared to those of the analogous molecules C3N, SiC2N, and C3P. Implications in the interstellar and P-doped SiC vaporization processes are discussed.