Research on the evaluation of the two characteristic dimensional parameters (crystal length and width) of rodlike urea crystals is proposed. The two-dimensional crystal growth and the corresponding crystal aspect ratios (AR) are highlighted during the evaluation. Various particle size analysis methods are then introduced to investigate two-dimensional growth mechanisms. Improved crystal morphology (varied from rodlike to columnar), crystal size distribution (coefficient of variation = 31.4), and AR (4.97) are obtained by the proposed operation profile (increasing cooling rate from 0.05 to 0.40 degrees C min(-1) and stable stirring rate of 300 rpm).