A density functional theory study on the geometrical structures and probable dissociation channels of CrP m + (m=2, 4, 6, 8) clusters has been performed. Our results reveal that the tetrahedral P 4 structure and linear P 2 structure are two stable units in CrP m + clusters relatively. The lowest energy structures of CrP m + clusters are constructed by bonding Cr with P 4 unit or P 2 unit. The bond between Cr and P 4 unit or P 2 unit is much weaker than the bond between P atoms in P 4 or P 2 unit. The most probable dissociation channel for CrP 8 + cluster is the detachment of P 4 unit or P 2 unit. Our conclusions are consistent with the previous laser photodissociation experiments.