Abstract: The mechanism of coke formation in FCC process was studied. It was concluded that asphaltene, resin and the colloidal system composed of them were the closely impact factors on coke formation. The test results show that adding the right amphiphile with similar structure to resin into the feedstock as residue dispersant can perform better dispersion and reduce the additional coke. Due to some flaws in conventional coke reducing methods, such as ultrasonic method and emulsion method, an optimal multiple scattering method was proposed to characterize the dispersion effect. The stability of the feed using right amphiphile can be increased by 23.5%.