Orbifold is a generalized manifold, which is a topological space with of singular points. The weighted projective space CPn(A) was blown up at a singular point, using the method of algebraic geometry. and the change of all twisted sectors and degree was studied shifting numbers after blowing up. The Chen-Ruan cohomology ring of the blowup was calculated and then the difference was showed from the Chen-Ruan cohomology ring of to the one of CPn(A)its blowup.