Objective  To determine the cycloplegic effects of 1% cyclopentolate on myopic children， using residual accommodation as an objective measurement. Methods  A total of 40 children with a mean age of 12.5±2.0 years were included in this case series study. Mean spherical equivalent of the right eyes was -2.52±1.05 D. One percent cyclopentolate was administered 3 times at 5 min intervals. After the third installation， far and near accommodative responses were measured at 25 min， 50 min， 75 min， 100 min， and 125 min using an open-field autorefractor （Grand-Seiko， WAM-5500）. The difference in the accommodative response between these 6 m and 33 cm was considered to be residual accommodation. Repeated measurement was used to evaluate the differences at the different time points. Results  The respective distance accommodative responses at the 6 time points were 0.27±0.79 D， 0.20±0.73 D， 0.14±0.61 D， 0.08±0.52 D， 0.11±0.40 D and 0.09±0.56 D and the differences were significant （F=6.18， P<0.05）. The respective near accommodative responses were 1.15±0.98 D， 0.42±0.81 D， 0.34±0.80 D， 0.16±0.69 D， 0.31±0.61 D and 0.32±0.76 D and the differences were significant （F=5.25， P<0.05）. The respective residual accommodations were 0.88±0.73 D， 0.22±0.55 D， 0.20±0.56 D， 0.08±0.61 D， 0.19±0.48 D and 0.24±0.45 D， and the differences were significant （F=7.28， P<0.05）. Conclusion  1% cyclopentolate is effective in paralyzing the ciliary muscle of myopic children aged 8-15 years， and reaches the strongest effect at 75 min. It is relatively accurate to finish refractions between 25 min and 2 hours after the last installation of 1% cyclopentolate.