The nonlinear transfer matrix method is used to study the optical bistable characteristics of Sinc function photonic crystal with nonlinear micro cavity. The results show that the field strength in the nonlinear microcavity and bistable thresholds are different with the increase of number of cycles or the change of the position of the nonlinear micro cavity. The field strength decreases in the nonlinear microcavity and the bistable threshold increases with the increase of linear refractive index of the nonlinear microcavity.