Considering LU-SGS and GMRES have been successfully applied into unstructured grid finite volume method as two main implicit iterative methods, they are combined with p-multigrid method in this paper and the overall acceleration performance is studied. The convergence acceleration of p-multigrid method is achieved through the recursive iterative solving of different order polynomial approximations. In order to achieve better convergence effect, implicit scheme is implemented on the lowest-order approximation while explicit schemes are implemented on the higher-order approximations. The transonic inviscid flow around NACA0012 airfoil and ONERA M6 wing were simulated. The numerical results show that, compared with the explicit TVD-RKDG method, convergence rates for the p-type multigrid methods, which adopt LU-SGS or GMRES scheme on DG (P₀) layer, have been significantly improved, while the performance of GMRES iterative method is best and LU-SGS iteration is secondary.