We introduce a Gaussian Optical analysis method for a common five-components zoom lens, namely “3+2”. This model has covered a great many type of zoom lens forms by regarding some of components as dummy ones. Taking each component as a paraxial one, “3+2” program calculates the geometric optics through the whole zooming range. The output report will show the moving curve of each element. “3+2” can mutually share the information with ZEMAX through the extension feature of ZEMAX.