▎ 摘　　要

Graphene quantum dots (GQDs) have fascinating potential optical applications such as in living cell fluorescent imaging and luminescent sensors and devices. Therefore it is rather important to prepare GQDs with excellent optical performance and high stability. We report here a set of optimum parameters to synthesize GQDs by hydrothermal method, including hydrothermal temperature at 140 degrees C, hydrothermal time of 9 h and dialysis time of 24 h. By analyzing the parameters, we conclude a surface functional group assisted PL mechanisms of GQDs.