Currently, the giant magneto-impedance effect of amorphous wires is usually investigated on the hypothesis that demagnetizing field can be ignored. This hypothesis is not true for amorphous wires with small size. We propose a model for calculating the static magnetization and magnetic field distribution inside CoFe-rich amorphous wires, which divides the amorphous wire into coaxial and nonoverlaped circular rings with the same width and height and different radii. Calculating the impulse response of the demagnetizing field at point r to the magnetization in each ring, the impulse response matrix is obtained. Using the impulse response matrix, the static magnetization and demagnetizing field distribution in the amorphous wire placed in an uniform or non-uniform DC applied field can be obtained.