First-principles molecular dynamics has been applied to inquire into the melting behaviors of n-atom (n = 6,10) graphene quantum dots (GQD(6) and zigzag GQD(10)) within the temperature range of T = 0-500 K. The temperature dependence of the geometry of each quantum dot is thoroughly evaluated via calculating the related shape deformation parameters and the eigenvalues of the quadrupole tensors. Examining the variations of some phase-transition indicators such as root-mean-square bond length fluctuations and mean square displacements broadly proposes the value of T-m, = 70 K for the melting point of GQD(6) while a continuous, two-stage phase transition has been concluded for zigzag GQD(10). (C) 2017 Elsevier B.V. All rights reserved.