Graphene nanoribbons (GNRs) can be applied to transistors, mass sensors, and dust detectors. Suspended GNRs which connect terminals in electronic devices like bridges can be treated as edge-constrained GNRs. In this paper, edge-constrained GNRs of various sizes and initial strains are studied using molecular dynamics (MD) simulations. To induce strain in GNRs, bond lengths between carbon atoms of the initial configurations of GNR models are varied. The bond length of the energetically stable GNRs is estimated at 1.47 Å. At this bond length, GNRs obviously change the tendencies of their energies, amplitudes, and deformations. The relationships between the out-of-plane deformations and the sizes of GNRs, and between the out-of-plane deformations and strains of GNRs are studied. Under compressive strain, the out-of-plane deformation of GNRs is dominantly caused by buckling. The amplitude of the buckling decreases as GNRs elongate. On the other hand, under tensile strain, the out-of-plane deformation of GNRs is caused by ripples and thermal vibrations. The ripples show regular patterns. It is suggested we can control the amplitudes of the out-of-plane deformations and ripple patterns of GNRs by adjusting their strain.