Different amounts of FCC slurry oil and HVGO were added to Tahe atmospheric residue respectively.The colloidal stability and asphaltene agglomeration of atmospheric residue and mixed oils were characterized by means of the mass fraction normalized conductivity and the small-angle X-ray scattering technology (SAXS).The results indicated that the stability of Tahe atmospheric residue decreased with an increasing amount of these oil fractions.It was found that the decline of the colloidal stability was attributed to the component polarity difference between oil fractions and the atmospheric residue.Though the aromaticity of FCC slurry oil was higher than that of HVGO,the polarity of aromatics and resins of FCC slurry oil was lower than those of HVGO.So the degree of the colloidal stability was more seriously destroyed by FCC slurry oil.The dispersion of asphaltenes in Tahe atmospheric residue was changed by adding FCC slurry oil and HVGO.The particle size of asphaltenes increased along with the decline of the colloidal stability.