The invention discloses a strengthening method for idle slipping of a large-scale slip formwork. The strengthening method includes the following steps of steel form disengaging, wherein when cylinder wall concrete is poured into the bottom of a crossbeam in the middle of a cylinder, concrete pouring is stopped, a slip form platform continues to be lifted, and before the concrete is completely solidified, steel forms are separated from the concrete; inner steel form removing and reorganizing, wherein according to the thickness change of the cylinder wall above the crossbeam in the middle of the cylinder, inner wall and outer wall steel forms are removed, and the spacing between enclosing steel channels of the slip form platform is adjusted; idle slipping process checking and strengthening; overall checking and strengthening of slip forms from a lower opening to the top of the crossbeam; inner and outer form installing, wherein inner and outer forms are installed after rebars of the crossbeam in the middle of the cylinder are installed. Compared with the prior art, the limitation of 3.8 m height of the cylinder is broken through, the use range is wide, on-site safety and quality can be greatly improved, and on-site schedule can be accelerated greatly.