The present invention provides a multifunctional biological substance separation device comprising a housing, a spindle push rod running through the housing, a return device, a magnetic sleeve connecting ring and an electric actuator; the two ends of the spindle push rod both protrude from the housing, and one end of the spindle push rod is provided with a magnetic column; the magnetic sleeve connecting ring is provided on the spindle push rod in a sleeving manner, and one end, which is positioned outside the housing, of the magnetic sleeve connecting ring is provided with a magnetic sleeve; the return device is provided in the housing, a rid is used for enabling the spindle push rod to move in a direction away from the magnetic sleeve; and the electric actuator is connected to the magnetic sleeve connecting ring, and is used for enabling the magnetic sleeve connecting ring (comprising the magnetic sleeve provided thereon) to rotate. The present invention also provides a dehydration device a nd method, the device comprising a housing, a spindle pushrod, a magnetic sleeve and an electric actuator; wherein the spindle pushrod extends through the housing, with both ends of the spindle pushrod protruding from the housing, and the spindle pushrod can reciprocate back and forth along the housing, and one end of the spind le pushrod is provided with a magnetic column; the magnetic sleeve is sleeved on the magnetic column, and the magnetic column is positioned coaxially with the magnetic sleeve and located at the center of the magnetic sleeve, and one opened end of the magnetic sleeve is connected to the housing; and the electric actuator is provided within the housing and connected with the magnetic sleeve for rotating the magnetic sleeve. The present invention further provides a magnetic sleeve which is a cavity with one closed end and one opened end; the cavity sequentially comprises a connecting sleeve and a body sleeve which are arranged integrally from the opened end to the closed end; a circle of convex ring is arranged on the edge of the end of the connecting sleeve.