The energetic and structural evolutions of fcc Fe nanoparticles under heating process have been investigated by molecular dynamics simulations, and the phase transition between fcc and bcc phases is addressed. It is found that the solid-solid transition from fcc to bcc phase happens prior to the melting, accompanied with the particle shape from initial sphere into ellipsoid. The critical temperatures of phase transition and melting are inversely proportional to the particle diameters. It is demonstrated that high percentage of surface atoms may be beneficial to the phase transition of fcc Fe nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.