Geometric structures, electronic states and energies of GanP and GanP2 (n= 1—7) clusters have been studied using the density functional theory. Structural optimization and frequency analysis were carried out at the B3LYP/6-31G* level.All ground states of GanP and GanP2 (n=1—7) clusters have been obtained.Our calculations reveal that there exists a transition from planar to spacial structures at n=5 with increasing cluster size. The strong P-P bond is favored over P-Ga in GanP2 (n=1—7) clusters. Among different GanP and GanP2 (n=1—7) clusters, Ga3P,Ga4P, GaP2, Ga2P2 and Ga4P2 are more stable. Their stability tends to reduce with the increase of the number of total atoms.