A primary structure of a strut for bearing an aircraft power plant including a front part intended to be joined to an aircraft power plant and a rear part intended to be joined to a structure of the aircraft, the front part being formed from a box including an upper longitudinal member, a lower longitudinal member, and lateral panels. A main rib is located at an interface between the front part and the rear part. The rear part is formed from a set of four connecting rods. The first end of each connecting rod is joined to the front part of the primary structure and the second end of each connecting rod is joined to a separate interface for fastening to the structure of the aircraft. This allows a substantial simplification of the primary structure of a strut for bearing an aircraft power plant, which can have advantages in particular in terms of cost, mass, and simplicity of implementation and integration.