The recent studies at home and abroad on photonic crystal fiber (PCF) are introduced, referring to the large negative dispersion PCF, the band-gap and mode characteristics of photonic band-gap PCF, the wavelength-tunable effective frequency conversion, the flat supercontinuum (SC) and the highly effective and broadband Cherenkov radiation (CR). Moreover, the theoretical and experimental achievements on PCF in our laboratory are presented, including the new numerical method for analyzing the PCF, the large-negative-dispersion PCF, the study and design of anti-resonance guiding PCF (ARG-PCF) and three kinds of highly nonlinear PCF, the generations of the highly effective wavelength-tunable anti-Stokes signal, the flat SC from 470 to 805 nm, and the highly effective and broadband CR at visible wavelength.