The objective of this study was to investigate the effect of N-(β-ethyl sulfonate) aminoethyl sulfonate (SA), an inevitable impurity during the taurine production using the ethylene oxide synthetic route, on the morphology of taurine crystals (TCs). Crystal morphology was investigated under different SA concentrations and cooling rates, and the length-diameter ratio of TCs were statistically analyzed. The molecular dynamics simulation method was used to investigate the attachment of the SA molecules on TC faces and the reason for SA changing crystal morphology. The results showed that the average length-diameter ratio of TCs increased as the SA concentration and cooling rate increased. The dosage of 0.04 mol SA per kg H2O could bring in an more than 100% increase of the TCs average length-diameter ratio when the cooling rate was 30 K/h. An increase of approximately 3.8 times in the average length-diameter ratio was observed when the cooling rate increased from 6 K/h to 36 K/h with 0.02 mol SA per kg H2O added. The cooling rate in the crystallization process should be controlled to less than 12 K/h to obtain taurine products with an average length-diameter ratio less than 3. The simulation results showed that the presence of SA increased the attachment energy barrier of taurine molecules on all stable crystal faces and the crystal habit simulated by the modified attachment energy model was consistent with the experimental morphology. The reduction of (111 ?) face area ratio and the expansion of (102) and (102 ?) face area ratios were the fundamental reasons for high length-diameter ratio needle-like morphology of TCs in the presence of SA. In conclusion, this study provides insights into the role of SA in shaping the morphology of TCs and offers recommendations for optimizing the taurine production process.