The invention discloses a hoisting device for steel truss sections of a steel truss cable-stayed bridge and a hoisting method of the hoisting device. The device comprises a longitudinal movement track (3), wherein a front truss transporting trolley (4) and a rear truss transporting trolley (5) are sequentially arranged on the longitudinal movement track (3); a vertical lifting hoist (6) is further arranged above the longitudinal movement track (3). The device and the method have the characteristics that the construction workload is reduced, the construction cost is reduced, the construction time is shortened and the construction efficiency is improved.