The invention provides a casing device and a casing method based on top drive operation. The casing device comprises a locking assembly, wherein the locking assembly comprises a locking central spindle, a slips, an upper cam sleeve and a lower cam sleeve, wherein the locking central spindle is provided with a central hole penetrating through along the axial direction; the upper end of the locking central spindle can be connected with a top driver; the slips is sleeved outside the locking central spindle; a sleeve pipe is sleeved outside the slips; the upper cam sleeve is connected to the outer part of the locking central spindle in a sleeving way; the lower cam sleeve is arranged at the outer part of the locking central spindle in a sleeving way; the lower cam sleeve is located below the upper cam sleeve and is connected with the slips; an upper cam is arranged on the lower end of the upper cam sleeve; an upper clamp hook is arranged on the lower end of the upper cam; a lower cam is arranged on the upper end of the lower cam sleeve; a lower clamp hook occluded with the upper clamp hook is arranged on the upper end of the lower cam. The casing method adopts the casing device. The casing device based on top drive operation provided by the invention adopts mechanical drive, and has the advantages of simple structure, simplicity and easiness in operation, and high reliability compared with hydraulic drive.