The generation of high-repetition rate (f_rep ≥ 10 GHz) ultra-broadband optical frequency combs (OFCs) at 1550 nm and 1310 nm is investigated by seeding two types of highly nonlinear fibers (HNLFs) with 10 GHz picosecond pulses at the pump wavelength of 1550 nm. When pumped near the zero dispersion wavelength (ZDW) in the normal dispersion region of a HNLF, 10 GHz flat-topped OFC with 43 nm bandwidth within 5 dB power variation is generated by self-phase modulation (SPM)-based OFC spectral broadening at 26.5 dBm pump power, and 291 fs pulse trains with 10 GHz repetition rate are obtained at 18 dBm pump power without complicated pulse shaping methods. Furthermore, when pumped in the abnormal dispersion region of a HNLF, OFCs with dispersive waves around 1310 nm are studied using a common HNLF and fluorotellurite fibers, which maintain the good coherence of the pump light at 1550 nm. At the same time, sufficient tunability of the generated dispersive waves is achieved when tuning the pump power or ZDW.