In this paper, we consider the spectral radius of signless p-Laplacian of a graph, which is a generalization of the quadratic form of the signless Laplacian matrix for p=2. Let π=(d0,d1,…,dn-1)be a non-increasing sequence of positive integers and Gπthe set of graphs with degree sequence π. In this paper, we obtain some transformations for graphs in Gπthat do not decrease the largest signless p-Laplacian eigenvalue of a graph. Furthermore, if ∑i=0n-1di=2nand d2≥2, then we identify the graph maximizing the signless p-Laplacian spectral radius among Gπ. As an application, we get the extremal graph maximizing the signless p-Laplacian spectral radius among all unicyclic graphs.