The utility model relates to a ladder structure of an aerial ladder fire truck. The ladder structure comprises a guardrail and a bracket, wherein pedals are mounted on the bracket. The ladder structure is characterized in that a plurality of oblique beams are mounted between the adjacent pedals, and the intersection points of the adjacent oblique beams are on the pedals. An original horizontal-line-shaped crossbeam type foot lever structure is converted into a pi-shaped ladder foot lever structure, the sectional dimension of a main cross beam is reduced, mouth-shaped steel pipes are additionally arranged from the center to two sides along the direction opposite to the extension direction of a ladder and obliquely connected with the next foot lever, and the pitch of the foot levers remains unchanged. The pi-shaped ladder foot levers are different from existing horizontal-line-shaped crossbeam type foot levers and are improved in structure dimension and layout. In the premise of meeting the strength performance of materials, the reduction of dimension is beneficial to reducing weight of the ladder and increasing the height of the ladder. The optimization of structural layout is beneficial to improving the safety performance of the ladder structure.