Abstract: The calefacient effect of the enclosed plastic shed is remarkable but the relative humidity in the shed keeps high in South China during autumn and winter seasons. Experiment was conducted in enclosed plastic sheds with diffrent humidity elimination in order to dry organic wastes such as sewage sludge and waste plant tissue. Results show that the periodically mechanical ventilation for the enclosed plastic shed not only reduce relative humidity, but also keep ideal temperature. It is useful for drying waste plant tissue, but for the sewage sludge drying, it is not necessary to enclose the plastic shed.