The wedge cell of cholesteric liquid crystal device is designed and fabricated, and doping PM580 (exciton) in the cholesteric liquid crystal, the laser emission action is studied. There appear a series of parallel wedge edges of dislocation lines and different shapes of domain in the wedge cell. The planar state of alignment is confirmed. A second harmonic Nd:YAG 532 nm laser is adopted as a pump light beam, and then one-dimensional tunable laser radiation is obtained and its wavelength interval is approximately 1 nm and tuning range is about 17 nm. In the processs of interaction between the torques of LC and the surface anchoring of direction film, the pitch elongation takes place. The positon of photonic band gap is changed, so the laser radiation wavelength can be tuned in the band edge.