Objective To compare the characteristics of diurnal fluctuations in body weight of myopia-induced and normal C57BL6 mice. Methods The total body weight was measured during two consecutive days per 2 hours, and the features of weight changes were plotted and compared. Results With the same age, the weight of experiment group was larger than that of control group (p <0.05). Diurnal fluctuations of weight in both groups arrived an average of 1.3 ~1.6 grams, and appeared as a "sine curve" type without stable point in normal cases, however, the weight of myopia-induced mice was relatively stable in the afternoon. Conclusion The diurnal fluctuations in body weight of mice should attract attention. Myopia induction of C57BL6 mice may affect its characteristics; we recommended evaluating the body weight of experimental mice in a stable period, while normal mice weight measurements should be fixed point in time.