The invention discloses a large-drift-diameter packer used for an oil well. The large-drift-diameter packer used for the oil well comprises a releasing module, a packing module, an anchoring module and a lower connector module. The releasing module is mainly formed by a releasing connector, a releasing lock sleeve, a locking piece and a releasing shear pin, after setting by the packer, pressurization is continued to shear off the releasing shear pin, a releasing sliding sleeve rises, the releasing locking piece slides off, and a releasing upper structure is lifted out along with an oil pipe. The packing module is mainly formed by a locking ring, a rubber barrel thrust sleeve, a rubber barrel, a rubber barrel lantern ring, a rubber barrel sliding sleeve, a rubber barrel base and other parts. The anchoring module is mainly formed by an upper cone, a lower inner cutting sleeve, a cava locking ring, a cava barrel, a cava, a leaf spring, a stop collar and a lower cone. The lower connector module mainly comprises a lower connecting sleeve, a deblocking shear pin and a lower connector. Compared with a traditional packer, the large-drift-diameter packer is combined with a large-stroke oil well pump for use, good in sealing performance and high in anchoring reliability.