<p>Formaldehyde possesses both bactericidal and high volatile biochemical properties, which has the potential to be used as the soil fumigant. This study aimed to elucidate the adsorption/desorption and fumigation effects of formaldehyde in tobacco continuous cropping soil, thus verifying the possibility of using formaldehyde as a fumigant. Soil adsorption/desorption process was investigated in headspace flasks by the batch method and the results were fitted in kinetic and isotherm models. The fumigation experiment was investigated in boxes and tobacco growing experiment was conducted in outdoor pots. Adsorption equilibrium was reached at 12 h with an adsorption efficiency of 12.58%, and the increasing temperature decreased the saturation adsorption efficiency. The adsorption data were successfully fitted to the pseudo second-order kinetic model and the Freundlich isotherm model. The soil completed desorption at 3 h with a desorption efficiency of 78.88%. In the fumigation experiment, formaldehyde at 500 and 1000 mg·kg⁻¹ (without mulching) demonstrated fungicidal efficacy, effectively suppressing <i>Fusarium</i>. Pot experiment showed that 500 mg∙kg⁻¹ without mulching had a good growth promotion effect. The soil has weak adsorption properties for formaldehyde and desorbs rapidly, which is conducive to the volatilization and sterilization of formaldehyde. Based on the results of the fumigation and pot experiments, we recommend using 500 mg∙kg⁻¹ for fumigation without mulching and planting the crop directly after fumigation.</p> Graphical Abstract <p></p>