Adopting a dual mode of heating and hot air in a drying oven module to simulate indoor air flow mode, namely air drying mode, for soil drying. The air is clean and hot air that has undergone coarse filtration and activated carbon adsorption. The samples are stored and dried independently in separate rooms, which is clean and avoids cross contamination of the samples; Time saving; Effort saving; Save space; Improve soil drying efficiency and other characteristics. Mainly used for drying soil, sediment, and solid waste samples for heavy metal element analysis.