The invention belongs to the field of aviation test devices, and particularly relates to a strength test device for an intermediate case of an aeroengine with a large bypass ratio. The strength test device comprises an intermediate case test piece, a bearing assembly, a simulation case and a loading assembly, wherein an auxiliary installation joint, a B-section installation edge, a main installation joint lug set, a first support point and a second support point are arranged at an outer side of the intermediate case test piece, a bottom end of a triangular vertical post of the bearing assemblyis fixedly arranged on a foundation platform, a bearing beam and a bearing wall are arranged on the triangular vertical post, a top-end cross beam is arrange on the bearing beam and / or the triangularvertical beam and / or the bearing wall, a bottom end of a simulation high-pressure compressor case is arranged on the foundation platform, a top end is connected with a bottom end of the intermediatecase test piece, a bottom end of a simulation fan case is in bolt connection with the B-section installation edge, the loading assembly is arranged on the bearing assembly and is used for loading thetwo support points of the intermediate case test piece, a B section, the main installation joint lug seat and the auxiliary installation joint. By the strength test device, the workload can be reduced, and the strength test device is high in universality.