Molecular dynamics simulations of a single-chain polystyrene particle adsorbed on the substrate surface of silicon were investigated. The particles, with various molecular weights, were prepared from the initial conformation of a Flory state coil after a 1000 ps dynamics run at 300 K. The morphology of the single-chain particles on the surface and the process from the Flory state to the collapse regime in vacuum were examined. It was found that the height of the particles depends weakly on molecular weight, and the particles have an irregular shape, findings which are in good agreement with experiment observations. A simulated heating process for a polystyrene particle of 100 repeat units adsorbed on the surface was performed from 320 up to 460 K with a heating rate of 20 K/ns for 8 ns. When the temperature is lower than 400 K, the particle shape tends to round with time. The results correspond to the AFM observation of single-chain PMMA particles with a long period of standing at room temperature. When the temperature is higher than 400 K, it is found that the particle tends to spread on the surface with a heat release of about 400 kJ/mol chain.