The influence of inlet temperature of cooling water on the solidification of paraffin outside the coil tube was investigated.Numerical equations were set up to calculate the heat transfer inside the heat exchanger.The calculation of temperature fields of water and paraffin agreed well with experimental results.The temperature fields of paraffin near to the tube were different with different inlet temperatures of water，while the temperature fields far away from the tube were almost the same.The distribution of dimensionless temperature fields of paraffin was similar at different inlet temperatures of water，except for the region near to the phase interface.The interface moved faster at a lower inlet temperature of water.The moving rate of the interface slowed down at first，and became faster again when the interface was discontinuous.The results can provide the guidance for choosing the right inlet temperature of water for an appropriate solidification rate of paraffin.