Utilization of highly nonlinear fiber(HNLF) with relative large normal dispersion in which an improved scheme that applies the pulse chirp compensation technique is presented to further broaden optical spectrum of 40 GHz,1.2 ps optical pulse train is experimentally realized.In the scheme,the pulse is launched into the HNLF of the first section to generate the spectrum-broadened linearly up-chirped pulse,and re-compressed after propagating through a suitable length of conventional single-mode fiber(SMF) of the second section for the pulse chipr being compensated.At last,the pulse travels through the second HNLF for further optical spectrum broadening.The experimental results shows that the 3.28 nm increment of 10 dB spectrum bandwidth is obtained when the new scheme is implemented given the same HNLF length and input seed pluses,and the coherence properties of the original pulses are maintained.For 40 GHz pico second pulse train,the experiment confirms that this scheme provides an effecive means of pulse spectrum broadening in the HNLF when the peak power of seed pulse is confined by the EDFA output power and the high repetition rate of pulse laser.