Ordering some even-unicyclic graphs by their Laplacian spectral radii is the main research problem.An expanding transformation which changes the Laplacian radius of even-unicyclic graph S1 k is given.With the aid of the way to prove the expanding transformation,the largest three and the smallest one in the order of even-unicyclic graphs C(k+2,k)(k≥10)by Laplacian spectral radii are obtained.