In this paper, a brief mathematic method is used to analyze the compression effect of negative third-order and fourtii-order dispersion on soliton in nonlinear Schrodinger equation involved with high-order dispersion in the fiber with slowly decreasing dispersion. The mathematic expressions of the shift of the optimum compression length are got Their predictions agree quite well with either the known-experiment results or numerical simulation. At the same time, the research is also extended in the positive third-order dispersion and dark soliton.