Nanoparticles exist in two states in fluids: suspended and deposited. Their state changes with particle height during boiling, significantly affecting heat transfer performance. This study adopts molecular dynamics simulations to investigate how particle state transforms with initial height, and compares the mechanisms by which deposited and suspended nanoparticles influence boiling heat transfer. Results show that deposited nanoparticles exhibit the most pronounced effect in enhancing boiling heat transfer, due to the efficient solid-solid heat conduction with the heating wall. Suspended nanoparticles mainly acquire energy from the wall via thermal radiation and near-field conduction, acting as an indirect heat source to promote heat transfer to the fluid, though their effect remains weaker than that of deposited particles. Both nanoparticle states enhance boiling heat transfer more effectively than pure water, corresponding to a higher heating rate, a larger critical heat flux, and an earlier bubble nucleation time. When the particles are deposited, the maximum critical heat flux is 3.74×10^-4 eV/Ų·ps, which is approximately 32.1% higher than that of the suspended particles with 2.79×10^-4 eV/Ų·ps. Meanwhile, the earliest bubble nucleation time of the deposited particles is 344 ps, which is approximately 39.4% shorter than that of the suspended particles with 568 ps. Whether nanoparticles deposit depends on the competitive relationship between the particle-wall interaction force and the fluid thermal disturbance force. By varying the initial distance between the nanoparticle and the heating wall rather than prescribing the particle state a priori, and thereby analyzing particle trajectories and their impact on heat transfer performance, a critical state-transition height of hc = 1.0 nm is identified: nanoparticles with an initial height below this value eventually deposit on the heating wall, whereas those initially above it remain suspended. Under the conditions of this study, only the transformation of suspended particles to the deposited state is observed, and no re-suspension of deposited particles is found. Furthermore, based on the non-dimensional analysis method at the molecular characteristic scale, a quantitative relationship is established between the initial height of nanoparticles and the critical heat flux as well as the bubble nucleation time: q^*_CHF = 69.0·h^*-0.08, 0 < h^* < 3.2; q^*_CHF = 63.0·h^*-0.01, h^* > 3.2; t^* = 236.9·h^*0.18, h^* > 0. It reveals that the critical heat flux shows a decaying trend as the initial height increases, while the bubble nucleation time increases with height. Besides, the particle height influences both parameters markedly below the critical height, whereas its effect diminishes substantially above this threshold. This work elucidates the mechanism through which particle state and the transformation processes influence nanoscale boiling heat transfer, providing a theoretical foundation for enhancing boiling heat transfer.