A numerical simulation is performed to study effects of a vibrational heat surface on natural convection in a vertical channel flow. This subject is a kind of moving boundary problems, and the finite element method and arbitrary Lagrangian-Eulerian kinematics description method is then utilized. The main parameters of Rayleigh number, amplitude and frequency are taken into consideration, and the mechanisms are examined in detail. The results show that for the same Rayleigh number, natural convection of a vibration heat plate with a certain combination of frequency and amplitude is possibly smaller than that of a stationary state. According to the results, the critical frequency could be derived and expressed in terms of Rayleigh number and amplitude. (c) 2005 Elsevier Ltd. All rights reserved.