When crystalline particles with distribution of multiple characteristics are obtained in reactive crystallization, it is difficult to select which one is the most suitable crystalline particles. Therefore, it is important to evaluate the non-uniformity of crystal particle characteristics in reactive crystallization and to propose an operation strategy to solve the problem. Since the multiple characteristics of crystalline particles significantly affect crystallization operability and performance, all the characteristics must be uniform. One method to comprehensively evaluate the uniformity of multiple characteristics has been proposed as “Homogeneity” evaluation. It was reported that if agglomeration phenomena or morphological changes occur during crystal growth, the multiple characteristics change significantly, resulting in non-uniform qualities. Therefore, the uniformity of the multiple characteristics was evaluated using homogeneity for proposing improved reactive crystallization operation. The changes in the homogeneity of crystalline particles in the initial and growth stages of reactive crystallization were considered. It was found that the homogeneity of each stage differed depending on the crystallization conditions such as solution addition methods. From the viewpoint of designing the supersaturation, the homogeneity could be improved by combining the characteristic of the crystallization phenomena of the initial and growth stages. Thus, a new operation for quality improvement in reactive crystallization could be designed by using “Homogeneity” to comprehensively evaluate the uniformities of multiple characteristics.