The invention discloses a double-layer track plate asphalt mixture transverse deformation monitoring system and method. The system comprises: six FBG sensors, a double-deck rut board test piece, a ruttester, a fiber grating demodulation appearance and a monitor terminal, wherein the FBG sensors are installed in the inside and the surface of double-deck rut board test piece, and the double-deck rut board test piece is established inside the rut tester, and the FBG sensors are connected with the fiber grating demodulation appearance through fiber jumper wires, and the fiber grating demodulationappearance is connected with the monitor terminal through a data line. The invention can monitor the transverse deformation rule of the road surface and can also obtain the transverse deformation rule in the road structure.