The invention provides a small angle X-ray scattering double-model fitting method. The method includes: an acquisition step: acquiring a scattering intensity experimental spectrum of an analyzed object; a modeling step: constructing double models according to the characteristics of the scattering intensity experimental spectrum; and an analysis step: adjusting the adjustable parameters in a scattering intensity calculation formula model of isotropic scatterer and a scattering intensity calculation formula model of orientation scatterer to minimize the difference between a calculation spectrumobtained by adding the scattering intensity calculation formula model of isotropic scatterer and the scattering intensity calculation formula model of orientation scatterer together and the scatteringintensity experimental spectrum, thus obtaining parameters of the models. The invention also puts forward a double-model fitting system of small angle X-ray scattering. The invention provides betterdata support for nondestructive testing of an effective observation material mesoscale structure by small angle X-ray scattering.