Preparation, Stability and the optical properties of DMACB/PEK-c film were reported. The firms have good transmittance and improved stability. By quasi-waveguide methord, The refractive indices of the film, n(e) and n(o), were measured,which were 1.65800 and 1.63614 at 0.6328 mu m, respectively; the film's electrooptic coefficients, gamma(33) and gamma(13) were also obtained, which were 80.80pm/V and 32.88pm/V, respectively.