The tunable micro-cavity based on one-dimensional (1D) photonic crystal doped by KTP is designed. The optical transmission properties in the doped one-dimensional defect photonic crystals are analyzed using transfer matrix method (TMM). According to the electro-optic effect, the refractive index ellipsoid equation is established with the applied alternating current at both coordinate axes, and the characteristics of temperature-optics and modulation are studied. Numerical calculations and experimental results show that the tuning range is ~40 nm.