The invention relates to the technical field of tunnel engineering, in particular to a large deformation control method of a chlorite quartz schist stratum one-hole three-lane highway tunnel. The method comprises the steps of conducting tunnel expanding excavation and supporting working under forepoling based on a three-step annular excavation reserve core soil method, wherein double-layer steel frames are adopted to arches, side walls and inverted arches of the tunnel, fractional supporting is conducted, the corresponding reserved deformation is 90-120 cm when a first layer of the steel frameis established, and the corresponding reserved deformation is 45-60 cm when a second layer of the steel frame is established. According to the large deformation control method of the chlorite quartzschist stratum one-hole three-lane highway tunnel, the large deformation requirements are met; meanwhile, it can be ensured that a support structure is safe and stable, and the purpose that there is no intrusion or arch to be replaced is achieved.