The geometrical and electronic structures of ConCm (n=15, m=1,2) clusters are investigated using spin-polarized DFT calculations. ConC (n=25) and ConC2 (n=14) clusters of their ground-state structures different. From n=3, two C atoms are located apart from each other, we think, it is an important reason for Co catalyze C in to single walled carbon nanotubes effectively. The total magnetic moment of ConC2 (n=25) are lower than those of ConC (n=25) clusters, and they both alternated with odd and even numbers. By comparing the fragmentation energies of neutral and charged ConC and ConC2 (n=15) clusters, we conclude that the single walled carbon nanotubes obtained in experiment is electropositive. This conclusion is in good agreement with that from expersimental model