||We study the vectorlike fermion(VLF) loop effect in the charged Higgs production and decays. As for the constraints, we investigate b to s gamma, Higgs precision and direct search bound of VLF. We pay special attention to the elector-weak constraints since they are quite strong. We find that the branching ratio of H^+ to W gamma can be enhanced by one or two order of magnitudes while H^+ to W Z still remains at the same order. We find the production channel in which the resonance production of neutral heavy Higgs boson happens and then it decays into charged Higgs can be important in broad mass range. We estimate cross sections for production and decays of charged Higgs via H^+ to W (gamma/Z) at the LHC as well as discovery significance.