The massive and massless boson bound states in Kerr metric are discussed. It is found that the massless boson cannot be attracted by Kerr black hole to form bound states. In extreme Kerr geometry and large l cases, our results are in agreement with that of deFelic's, but we extend his result to arbitrary l and non-extreme Kerr geometry. For massive bosons, if the bound state conditions are satisfied, it is possible to form bound states in the extreme Kerr metric. Its energy mode, wave functions and bound states conditions are given.