A flow channel for experimental modeling of the structural reaction injection molding (SRIM) process, for producing composites with a sandwich-like structure. has been designed and constructed. It consists of a thin rectangular box, in which the reinforcing glass fabrics with different permeabilities are positioned parallel to each other. The core layer is a thick, porous mat. Location of the other denser and thinner reinforcing materials into the flow channel was symmetrical with respect to the spacer mat. The channel has transparent walls for observing propagation of the impregnation front in the spacer mat and in the reinforcing dense layers. Development of the impregnation front during filling the flow channel and the pressure profile in the gate were measured for non-foaming reactive polyurethanes. Enough good correspondence between the calculated and experimentally observed flow front position and pressure profiles was obtained.