A linear cutting stapler comprises: an upper jaw and a lower jaw (1) capable of closing or opening relative to each other. A staple cartridge (2) is disposed at a distal end of the lower jaw (1). The lower jaw (1) has a U shape, in which a striker (5) and a pushing rod are slidably disposed. The linear cutting stapler further comprises a safety mechanism. The safety mechanism comprises a safety piece (4), and an opening (52) opened on the striker (5) and for receiving the safety piece. The installation or removal of the staple cartridge (2) may drive the safety piece (4) to move in a direction perpendicular to the axis of the lower jaw (1), so that the safety piece (4) is disengaged from or engaged with the opening (52) of the striker (5). The linear cutting stapler has a simple structure, can be easily fabricated, and is safe and reliable.