The paper presents a new pitch generation model based on internal dependence of pitch contour. This model pays more attention to the impact of adjacent syllables' pitch contours on the current one. A new definition of concatenation cost is presented to measure the naturalness of pitch contours between every two adjacent syllables. Based on this definition, the model concentrates on how to remove unnatural pitch contours across concatenated places which are always the most unstable parts in the synthesized speech. This model can generate natural, fluent pitch contours and was proved to be able to catches the essential nature of pitch contour.