The invention provides a setting method for horizontal bearing force of gravity anchors. The method comprises the steps of: determining a relation between change of skid resisting force of a gravity anchor model and the number of times of start on natural calcareous sand via indoor model tests and drawing a scatter diagram; determining the skid resisting force and a bottom-soil body friction coefficient of the gravity anchor model and drawing a scatter diagram showing how the friction coefficient changes along with the number of times of start; obtaining a relation between the friction coefficient and a normalized displacement value according to the scatter diagram showing how the friction coefficient changes along with the number of times of start, which is drawn in the second step, and drawing a scatter diagram; according to the scatter diagram drawn in the third step, determining the relation between the friction coefficient and the normalized displacement value; according to the relation between the friction coefficient and the normalized displacement value and based on an admissible displacement quantity of a gravity anchor in engineering, determining a gravity anchor friction coefficient expression; according to the structure of the gravity anchor, the on-site soil texture conditions and the friction coefficient obtained in the fifth step, determining horizontal bearing force of the gravity anchor. The method can reduce manufacturing cost and installing cost of gravity anchors.