Nyquist pulses have important applications in the fields of optical communicatio n,microwave photonics,optical storage and all-optical sampling.To meet the spec ific requirements for the duty cycles of Nyquist pulses in different applications,a scheme for genera ting Nyquist pulses with adjustable duty cycles based on spectral broadening and chirp compensation is proposed.First, using the phase modulator (PM) as a time lens,the flat-top optical pulse generated by the intensity modulator (IM) is transformed into a flat optical frequency comb with spectral broade ning in the frequency domain;Then,the near-linear chirp introduced by the phase modulation is compe nsated by standard single-mode fiber (SSMF),resulting in a pulse-width compressed short pulse without c hirp;Finally, continuous adjustment for the duty cycle of Nyquist pulses is achieved using an optical filter with adjustable center wavelength and bandwidth.Nyquist pulses with a period of 100 ps,a pulse width of 4.0 ps to 12.6 ps and an adjustable duty cycle of 4.0% to 12.6% are obtained at the radio frequency of 10 GHz by numerical simulation.The roll-off factors are relatively low,rangin g from 0 to 0.127,and the root mean square errors with the ideal pulses are 0.16%—0.58%.The results s how that this scheme can realize the generation of Nyquist pulses with flexible and adjustable duty c ycles.