I am working on numerical method of Multigrid. What's the available implementation(solver) (actually used in scientific computation) of multigrid method?
There are many libraries that provide widely used implementations of multigrid methods. Most of the available finite element libraries do to the best of my knowledge (certainly the one I work on, deal.II, does). There are also widely used implementations of algebraic multigrid methods, most notably from the ML and hypre packages that you can most easily access via the Trilinos and PETSc projects.