The generation and evolution processes of noise-like pulses (NLPs) in an all-normal-dispersion nonlinear polarization rotation (NPR) mode-locked Yb-doped fiber laser are numerically and experimentally investigated. We demonstrate that the amplitude modulation induced by reverse saturable absorption and the peak-power-limiting effect of the NPR plays a key role in the formation of fine-structure oscillations of NLPs. The width variation of the NLPs is also discussed in detail. (c) 2017 Optical Society of America