Abstract: A drilling device and a drilling construction method for an electric power iron tower foundation are provided. The drilling device includes a hydraulic drilling unit, a multi-way connector, a compressed air conduit, a plurality of air compressor units, an air duct, a dust removal unit and an operation bench. The hydraulic drilling unit is capable of moving among a plurality of drilling platforms and among a plurality of hole positions on the plurality of drilling platforms and performing a drilling operation. The plurality of air compressor units are disposed in a fixing and mounting region that is between the plurality of drilling platforms, where compressed air outputted by the plurality of air compressor units flows jointly through the multi-way connector and then is transmitted to the hydraulic drilling unit through the compressed air conduit.