Supercontinuum generation is one of the most important applications of photonic crystal fibers. An optical pulsed laser, of pulse width smaller than 1 ns, repetition rate about 6.85 kHz, average output optical power lower than 100 mW, and central wavelength near 1064.5 nm, is used to pump a segment of highly nonlinear photonic crystal fibers with length about 15 m, air hole diameter 2.205 μm, hole-hole space 3.359 μm, average core diameter 4.5 μm, zero dispersion wavelength 1016 nm. Then a flat supercontinuum of spectrum span over 1100 nm is obtained. The supercontinuum is also a series of optical pulses, whose repetition rate is the same as the pumping pulse, and each single pulse is broaden due to the dispersive effect. Except the peak at 1064.5 nm, which is generated by the residual pumping optical power, the power fluctuation is within 10 dB over the whole measuring range of 600~1700 nm. Therefore, an excellent supercontinuum, of low optical power and flat spectrum response, is obtained. It is very useful in various optical measurements, such as ultra-broadband super-width dispersion measurement of fibers.