The embodiment of the invention provides a qualitative motion modeling method based on a Voronoi graph and application of the qualitative motion modeling method to big data privacy security. The method comprises the following steps: determining space objects, and establishing a space object Voronoi diagram to obtain a proximity relation between the space objects; analyzing the relationship and rule between the dynamic change of the Voronoi graph and the motion of the space object to research a qualitative representation method of the position of the space object and evaluate the cognitive rationality of the qualitative representation method; Constructing a concept neighborhood of the proximity relation by taking the proximity relation as a representation primitive so as to realize the qualitative representation of a plane space and a motion path; determining a motion path of the information packet between servers in the big data platform based on the qualitative representation; and encrypting the information packet by using the motion path represented qualitatively.