Using density functional theory associated with the B3LYP method with 6—31G* basis set, we have carried out the optimizing calculations of the geometry, electronic state and vibrational frequency for GamP-n(m+n≤5) clusters, moreover, discussed the vertical detachment energy of GamP-n and the adiabatic electron affinities of GamPn. The results show that the structures with singlet have higher symmetry, while the one with doublet has lower symmetry.