The Galerkin finite element numerical model was established to analyse the freezing and thawing process for frozen food processing, to predict the freezing time for any shape foods at different freezing conditions, and to investigate the effect of freezing parameters on the freezing process. It was proved that the method is effective to solve the Stefan problem for its accuracy, stability and convergence. The results obtained show that the food shape and size, freezing air temperature and freezing air velocity are the important factors affecting freezing rate, and the freezing parameters should be matched with the thermal conductivity of food. Based on the analysis, the control values of the final central temperature for three typical shapes were recommended. (C) 2003 Elsevier Ltd. All rights reserved.