The invention discloses a steam-driven steam injection well under-well reservoir seal control device and a method. The device comprises a release piston, a center pipe, a releasing piston and a tapping pin orderly connected from top to bottom, wherein the releasing piston is covered with a stamping switch short nipple; the outer wall of the releasing piston is covered with a packer inner pipe and inserted into a steam-injection packer via the packer inner pipe; the upper end of the packer inner pipe extends till wrapping the whole center pipe in the packer inner pipe, and then is connected with the lower end of the stamping switch short nipple over; the lower end of the packer inner pipe is connected with the outer wall of the tapping pin via a centralizing connection guide sleeve; the lower end of the steam injection packer is connected with a ball valve; and the lower end of the tapping pin extends into the ball valve to be abutted against the interior of the ball valve. Ground existing equipment is fully utilized and the steam injection channel is started via an oil pipe stamping method and closed via a casing pipe stamping method; and the steam-driven steam injection well under-well reservoir seal control device is easy to operate and safe and reliable.