As well known,cell-penetrating peptides (CPPs),a class of short peptides with positive charges,are capable of translocating directly through the biomembrane in an energy-independent fashion.CPP therefore becomes an ideal candidate for delivering cargos of various sizes into cell,although the penetrating mechanism of CPPs is still largely unknown.Here,molecular dynamics simulation method is applied to demonstrate the role of transmembrane potential for the formation of nanoscale hydrophilic holes that direct CPP translocation.