A handle assembly and a surgical stapler including the handle assembly is provided, including a first handle and a second handle, both can rotate around a first pivot pin. Either the first or the second handle is provided with a slider and a sliding slot. When the slider moves from a first section of the sliding slot to a second section, the two handles become linked. The first handle can still be squeezed even if the stapler has not reached the firing position, but the second handle will not rotate and the stapler will not be fired; featured by the design of two torsion springs and two pivot pins, the first and the second handle are pivotally attached and can be rotated around the same rotation center that remains unchanged in both the insurance position and the firing position, rendering an enhanced stapler structure stability and improved operator experience.