The spectra of the lateral laser radiation in nematic liquid crystal (NLC) laser devices are studied, and the characteristics of the laser radiation are deeply analyzed. Two types of NLC cells of standard NLC cell and SU-8 grating based NLC cell are fabricated and injected with a mixture of NLC TEB30A and laser dye PM597, respectively. A frequency-doubled Nd: YAG solid-state pulsed laser with a wavelength of 532 nm is used as the pump source. Random lateral laser radiation in the wavelength of 575-600 nm is observed in the standard NLC cell. Whereas, in the SU-8 grating based NLC cells with periods of 100 μm and 8 μm, the spectrum of the multi-wavelength lateral laser radiation is obtained. With the increase of the pump energy, the strongest lateral laser radiation peaks appear at 583-585 nm and 588-592 nm, and the FWHM is about 0.3 nm. According to the theory of the optical waveguide and analysis of the device structure, the introduction of the SU-8 grating into the standard NLC cell enhances the optical waveguide effect of the LC device and induces multi-wavelength laser radiation.