A portable extraction device for extracting at least one constituent from a substance by an extraction fluid, comprising: an extractor for receiving and mixing the substance and the extraction fluid, wherein the extraction fluid is a subcritical fluid, such that the constituent in the substance is dissolved into the extraction fluid under a predetermined pressure and a predetermined temperature; an evaporator, disposed below the extractor, and interconnected to the extractor, wherein the evaporator receives the extraction fluid including the constituent from the extractor, and heats the extraction fluid including the constituent so as to gasify the extraction fluid and therefore separate the constituent from the gasified extraction fluid; a condenser, disposed below the evaporator, connected to an upper part of the evaporator via a first pipe, and connected to the extractor via a second pipe, wherein the condenser receives the gasified extraction fluid from the evaporator via the first pipe, liquefies the gasified extraction fluid, and transmits the liquefied extraction fluid to the extractor via the second pipe; wherein the extractor comprises: openings on a bottom of the extractor fluidly connected to the evaporator, and a demountable vessel rotatably sleeved in the extractor, comprising an inlet, the inlet being aligned with the second pipe, openings on a bottom of the vessel; a lid, wherein the substance to be extracted is present in the extractor via the vessel covered by the lid; wherein when the inlet is in a first position by the rotation of the vessel, the openings of the vessel and the openings of the extractor are not aligned with each other and therefore the openings (1131, 1133) are closed, and the extraction fluid enters the vessel via the second pipe and the inlet; or when the inlet is in a second position by the rotation of the vessel, the inlet is disconnected from the second pipe, the second pipe is closed by a side wall of the vessel, and the openings of the vessel and the openings of the extractor are aligned with each other and therefore the openings (1131, 1133) are opened. an extractor for receiving and mixing the substance and the extraction fluid, wherein the extraction fluid is a subcritical fluid, such that the constituent in the substance is dissolved into the extraction fluid under a predetermined pressure and a predetermined temperature; an evaporator, disposed below the extractor, and interconnected to the extractor, wherein the evaporator receives the extraction fluid including the constituent from the extractor, and heats the extraction fluid including the constituent so as to gasify the extraction fluid and therefore separate the constituent from the gasified extraction fluid; a condenser, disposed below the evaporator, connected to an upper part of the evaporator via a first pipe, and connected to the extractor via a second pipe, wherein the condenser receives the gasified extraction fluid from the evaporator via the first pipe, liquefies the gasified extraction fluid, and transmits the liquefied extraction fluid to the extractor via the second pipe; a demountable vessel rotatably sleeved in the extractor, comprising an inlet, the inlet being aligned with the second pipe, openings on a bottom of the vessel; a lid, wherein the substance to be extracted is present in the extractor via the vessel covered by the lid; wherein when the inlet is in a first position by the rotation of the vessel, the openings of the vessel and the openings of the extractor are not aligned with each other and therefore the openings (1131, 1133) are closed, and the extraction fluid enters the vessel via the second pipe and the inlet; or when the inlet is in a second position by the rotation of the vessel, the inlet is disconnected from the second pipe, the second pipe is closed by a side wall of the vessel, and the openings of the vessel and the openings of the extractor are aligned with each other and therefore the openings (1131, 1133) are opened.