Dual-wavelength semiconductor lasers have various potential applications in microwave photonics and laser radars fields. Monolithic integrated dual-wavelength DFB laser with equivalent-chirp sampled grating is proposed and investigated theoretically in this paper. The grating of the dual-wavelength DFB laser is designed by the reconstruction-equivalentchirp technique. The effects of the grating with different phase-shifts and different chirp ratios on the characteristics of the dual-wavelength DFB laser are theoretically demonstrated. The results proposed in this paper have great reference value for fabricating dual-wavelength semiconductor lasers.