The principle of field synergy is to simulate the freezer optimization of input fan location in this study. The parameters U, V, W and input position of fan are calculated to simulate ooptimization of fan position of freezer. Temperature and velocity fields are simulated by COMSOL Multiphysics software. Freezing degree is calculated by field synergy mean square root method in this research. In this study, high efficient coolant tube is used to assist freezer. The simulation result shows that field synergy angle decreases while freezing degree increases. It is very obvious that the best input position of fan leads lower field synergy angle. Cu coolant tube has best performance for cooling efficiency.