A linear cutting stapler comprises: an upper jaw and a lower jaw (5) capable of closing or opening relative to each other. A staple cartridge (51) is disposed at a distal end of the lower jaw (5). The lower jaw (5) is U-shaped, and has a staple driving rod (3) and a blade driving rod (4) slidably disposed therein. The linear cutting stapler further comprises a safety mechanism. The safety mechanism comprises an engagement member. A notch fitting the engagement member is disposed on a bottom surface of the staple driving rod (3). The safety mechanism further comprises a floating block (1). The floating block (1) may perform longitudinal displacement in the lower jaw (5). When the floating block (1) is pressed against the staple cartridge (51) or an anvil (6), a top end of the engagement member is driven to perform longitudinal displacement, so that the engagement member is separated from the notch. The linear cutting stapler has a simple structure, is easy to be fabricated, and is safe and reliable.