Disclosed are a device and a method for determining the solubility of elemental sulfur in a sulfur-containing gas. The device includes a displacement pump, a first sampler, a high-temperature box, a back-pressure pump, a control valve, an adsorption tank, a low-temperature box, a flow meter and a collection tank. An outlet of the displacement pump is in communication with an inlet of the first sampler; an outlet of the first sampler is in communication with a first inlet of the control valve; a second inlet of the control valve is in communication with an outlet of the back-pressure pump; an outlet of the control valve is in communication with a first opening of the adsorption tank; a second opening of the adsorption tank is in communication with the flow meter; and a third opening of the adsorption tank is in communication with the collection tank.