The invention discloses a method for improving a lift drag ratio of a supercritical airfoil of a large passenger aircraft. The method is implemented through the step of setting a bulge with a limited length, a limited height and a certain shape at a position near a shock-wave occurrence position of a certain supercritical airfoil, wherein the shape function of the shock-wave controlled bulge is as follows: fB(xB)=hBH(xB), wherein H(xB) refers to the modification of a Hicks-Henne type function and is shown in the specification, hB refers to the height of the shock-wave controlled bulge, lB refers to the length of the shock-wave controlled bulge, and cB refers to the non-dimensional chord length of the shock-wave controlled bulge. The method provided by the invention has the advantages thatthe shock-wave controlled bulge is obtained by minimally changing the existing supercritical airfoil, and no other additional equipment is required, thereby achieving the purposes of reducing the strength of shock waves, improving the drag divergence Mach number and then improving the lift drag ratio of the supercritical airfoil of the large passenger aircraft.