Thepurposeofthispaperistostudythecascadicmultigridmethodforthesecondorderellipticproblemswithcurvedboundaryintwo-dimensionwhicharediscretizedbytheisoparametricfiniteelementmethodwithnumericalintegration.WeshowthattheCCGmethodisaccuratewithoptimalcomplexityandtraditionalmultigridsmoother(likesymmetricGauss-Seidel,SSORordampedJacobiiteration)isaccuratewithsuboptimalcomplexity.