The B-doped (100) CZ-Si single crystal films were implanted with 50 and 100 keV hydrogen ions in the concentration range of 1015-1017H+/cm2. The implanted specimens were electron irradiated at l000keV in HU-1300 HVEM. It was found that the electron irradiated defect density was higher ia Si with no hydrogen than in hydrogen implanted Si at the same irradiation condition within the temperature range 298-573 K. When hydrogen implanted Si films were heated insitu in HVEM from room temperature to 823 K, The hydrogen blisters were formed in k at about 473 K. The critical hydrogen concentration in Si for the formation of blister was 9×1016 H+/cm2. Hydrogen blisters had the form of convex lens with diameter 1000-5000 nm. The blister number density was about 1017/m2 in the 1017H+/cm2 implanted Si The formation of blister is related with the dissosiation of silicon-hydrogen bond in Si.