The invention discloses an adjustable ladder supporting frame, and relates to the field of power construction. During voltage transformer\current transformer construction, due to the secondary cable pipe penetrating influence, a ladder cannot directly lean on an equipment rod while can only lean on a cable pipe, and the safety using requirement cannot be met. The adjustable ladder supporting framecomprises a supporting frame body, embracing claws and a connecting fixing device. The supporting frame body comprises a left supporting rod and a right supporting rod which are symmetric left and right. The embracing claws include the arc left embracing claw and the arc right embracing claw which are arranged at the front end of the left supporting rod and the front end of the right supporting rod correspondingly and can forwards and backwards contract and stretch and be fixed. An adjustable cross rod is arranged between the rear portions of the left supporting rod and the right supporting rod so that the distance between the rear portions of the left supporting rod and the right supporting rod can be adjusted. An adjustable connecting locking device is arranged between the front portions of the left supporting rod and the right supporting rod so as to lock the equipment rod through the embracing claws. The technical scheme can conveniently adapt to single ladders different in size,the single ladder construction safety is improved, safety accidents are reduced, and life guarantee and operation efficiency are improved.