The invention relates to a system for pretreating moso bamboo shells by means of a steaming device and a flattening device. The system comprises a hair removal device, a soaking tank, the steaming device, a washing tank, an airing rack, the flattening device and a pressing machine. The interior of a hot pressing plate is arranged to be in the shape of a cavity used for containing heat conduction oil. A circulating oil path is formed by the cavity via oil conduction pipes, a conveying pump and an oil storage box. An electric heating assembly is arranged in the oil storage box. Partition plates are arranged in the cavity and divide the cavity into a circuitous runner allowing the heat conduction oil to flow. According to the technical scheme, the bamboo shells can be effectively flattened, and reliable support is provided for machining and utilizing of the bamboo shells.