We investigated the high harmonic generation (HHG) from the interaction of intense femtosecond laser pulse and rare gas in the hollow core photonic crystal fiber(HCPCF) as new optical waveguide materials. The grating-assisted phase matching (GAPM) of HHG in HCPCF is demonstrated to be experimentally feasible and is especially suitable for photon energies in the range of 100~1keV. The conversion efficiency is expected to be dramatically improved for the longer interaction length provided by the very low loss of HCPCF.