Controlling unabridged graphene-lubricated layers and extending their last times can extend the service life of polymer moving components. The friction reduction behaviors of graphene nanoplatelets (GNP) on the tribology performances of high-density polyethylene (HDPE) were studied based on friction experiments. The mechanical properties, coefficient of friction (COF), surface topography, tribo-layers wear synthetically charactered to analyses the friction reducing processes. The results showed that the GNP presented a limited friction reduction to HDPE, and it could be controlled by the mass contents of GNP, load and speed. The proper content of graphene maintained the effective GNP tribo-layers for a long time and led to a long duration of friction reduction. Decreasing load or speed weakened the wear processes, which was useful for maintaining the effective GNP tribo-layers for a long time, and reduced the COF. The knowledge will provide experimental support for improving the self-lubricating performance and abrasiveness of polymers.