In　this　paper,　we　propose　a　scheme　for　realizing　controlled　phase　gate　of　transmon　qubits　by　combining　the　unconventional　geometric　phase　and　the　inverse　Hamiltonian　engineering.　The　scheme　possesses　built-in　fault　tolerance　and　can　be　implemented　in　only　one　step　without　additional　single　qubit　operations　on　each　transmon　qubit.　In　addition,　the　Rabi　frequencies　of　the　designed　driving　fields　are　smooth　and　vanish　at　boundary,　so　that　the　driving　fields　can　be　easily　turned　on　and　off.　Numerical　simulations　show　that　the　controlled　phase　gate　is　robust　against　several　types　of　noise　and　the　decoherence　factors.　Thus,　the　scheme　may　provide　an　alternative　approach　in　constructing　controlled　phase　gate　with　superconducting　qubits.