Triboelectric generators, which can directly transform energy from our living environment into electricity, are self-powered component for wearable devices. Flexible and transparent triboelectric generators (FTTGs) with high output power densities are urgently needed for wearable electronics. By introducing graphene (G) and indium tin oxide (ITO) as transparent electrodes and optimizing the electrode structure, a FTTG with polyimide (PI) and polyethylene terephthalate (PET) as friction layers and graphene (ITO) as top (bottom) electrode was obtained and it has a large output power density of 10.1Wcm(-2), which is over four times larger than previously reported FTTGs ca. 2Wcm(-2). Moreover, the output voltage of the graphene-based FTTG is as large as 56V, and it exhibits excellent cycling behavior. The effects of electrode structure on the performance of FTTG have been analyzed and corresponding mechanism has been discussed. Light-emitting diodes (LED) can be easily powered by the FTTG, suggesting its potential application in harvesting electrical energy from human activities by using flexible and transparent devices.