The present invention discloses a tissue closure device, a tissue closure assembly and a medical instrument. The tissue closure device comprises a base, a pressure plate cooperating with the base, and a staple pushing sheet. The pressure plate is rotatable relatively to the base, and comprises an open position and a closure position. When the pressure plate is located at the closure position, the pressure plate cooperates with the base to form a first accommodating space for accommodating part of a tubular tissue. The staple pushing sheet comprises an original position and a staple closure position； and the original position is located at the proximal end of the staple closure position and the first accommodating space. The tissue closure device further comprises a staple accommodating portion which is arranged at the distal end of the base and configured to accommodate a closure staple. The staple pushing sheet and the staple accommodating portion are configured to cooperatively drive the closure staple in the staple accommodating portion to deform. In the present invention, a bundled pouch with a gathered center is formed through the tissue closure device, so that risks of stoma fistula arising from subsequent anastomosis through a circular stapler are reduced； and the surgery cost is reduced.
