A linear surgical stapler includes upper and lower jaws, a staple cartridge arranged at a distal end of the lower jaw, a firing piece movably arranged relative to the staple cartridge, and a cutter advancer having a cutter. The firing piece and the cutter advancer are kept relatively still. The linear surgical stapler also includes a lower safety block having a raised stopper. When the linear surgical stapler is in an initial state without loading the staple cartridge, at least a part of the raised stopper is arranged on the movement path of the firing piece. The safety mechanism of the linear surgical stapler is structurally simple, convenient to process, also safe and reliable.