In this work, the rheology and the microstructures of thermoset polymer composites reinforced with glass fibres, such as Bulk Moulding Compounds (BMC) and Sheet Moulding Compounds (SMC), are analysed. Firstly, the rheology of BMC is studied by using dedicated simple and plane strain compression rheometers. Experimental results emphasize the influences of the strain rate, the type of mineral fillers, the volume fraction of fibres as well as the temperature on the BMC rheology. 1D and 3D non-linear viscoelastic rheological models are proposed to reproduce the behaviour of BMC. Secondly, the...