The invention provides a satellite-borne phased array plane support system. The system comprises penetrating type feeding assembly installation structure units in the plane plate shape to realize penetrating installation of feeding assemblies; array plane back orthogonal reinforcing rib structures located on the backside of a support base body and penetrating through a phased array plane along the length direction according to the distribution of the feeding assembly installation structure units to realize unification of light weight and high rigidity of the system; an enclosed array plane enclosure frame structure which connects the feeding assembly installation structure units and the reinforcing rib structures to an integral body to realize structural integration; handle installation structures arranged at two ends of the enclosure frame structure and used as reinforcing structures; and array plane fixing and installation expansion structures arranged at the top surface and the bottom surface of the enclosed array plane enclosure frame structure. Therefore, according to the system, the array plane supporting structure is advantaged by large scale, light weight, and high rigidity, compared with a satellite-borne phased array, the bearing requirement and the mechanical rigidity and intensity requirements are satisfied, the requirement of light weight is also met, and an important contribution is made to the reduction of the weight of the whole phased array.