A process for producing a grease composition which is capable of homogeneously and surely dispersing a non-fluorine-based base oil blended with a thickening agent and a fluorine-based base oil blended with a thickening agent. A mixture of a non-fluorine-based base oil blended with a first thickening agent and a fluorine-based base oil blended with a second thickening agent that are not mutually compatible is homogeneously treated at a shear rate of 150 s−1 or higher to form a morphology structure in which one of the non-fluorine-based base oil and fluorine-based base oil is homogeneously dispersed in a particulate form having a mean particle diameter of not more than 25 μm in the other base oil.