When UV-Nanoimprint Lithography(NIL) is used in manufacturing gratings of Distributed Feedback Laser Diodes(DFB LDs), the resist often turns into a high polymer after curing and can not be eliminated completely. To eliminate the residual resist, a multi-mask layer process was demonstrated. In this process, a 50 nm SiO2 hard mask was deposited between the wafer and the UV-curable resist and then traditional nanoimprint lithography based on soft stamp UV-imprinting was executed. Following that, the Inductively Coupled Plasma(ICP) dry etching was used to transfer the pattern on the substrate. Finally, it was rinsed with Buffered Oxide Etchant(BOE)for a few seconds .The effect of etching time on the duty ratio of grating was explored and the grating morphologies processed by traditional method and proposed method were compared. A scanning electron microscope image of rinsed grating shows that the grating with about 240 nm pitch and 82 nm depth offers a clean surface and a good feature. Therefore. The proposed method not only can eliminate the residual resist effectively but also can avoid the morphologic damage.