A detailed theoretical study is performed at the B3LYP/6-311G(d,p) and G3B3 (single-point) levels as an attempt to explore the reaction mechanism of CH with C3H6. It is shown that the barrierless association of CH with C3H6 forms two energy-rich isomers CH3-cCHCHCH(2) (1), and CH2CH2CHCH2 (4). Isomers 1 and 4 are predicted to undergo subsequent isomerization and dissociation steps leading to ten dissociation products P-1 (CH3-cCHCHCH + H), P-2 (CH3-eCCHCH(2) + H), P-3 (cCHCHCH(2) + CH3), P-4 (CH3CHCCH2 + H), P-5 (cis-CH2CHCHCH2 + H), P-6 (trans-CH2CHCHCH2 + H), P-7 (C2H4 C2H3), P-8 (CH3CCH + CH3), P-9 (CH3CCCH3 + H) and P-12 (CH2CCH2 + CH3), which are thermodynamically and kinetically possible. Among these products, P5, P6, and Pi may be the most favorable products with comparable yields; P-1, P-2, and P-3 may be the much less competitive products, followed by the almost negligible P-4, P-8, P-9, and P-12. Since the isomers and transition states involved in the CH + C3H6 reaction all lie lower than the reactant, the title reaction is expected to be fast, which is consistent with the measured large rate constant in experiment. The present study may lead us to a deep understanding of the CH radical chemistry.