The implicit schemes for solving Euler equation are investigated on unstructured grids, including LU-SGS,GMRES and improved LU-SGS schemes. By Roe numerical flux and Van Albada typed limiter, the traditional LU-SGS and GMRES schemes are explored, and the improved LU-SGS scheme is developed by adding the error compensation of high order term. In addition, the transonic inviscid flow around NACA0012 airfoil and RAE2822 airfoil as the examples are calculated. The numerical experiments indicate that the error c...