Hydrogenated　amorphous　silicon　(a-Si:H)　films　with　high　and　same　order　of　magnitude　photosensitivity　(similar　to　10(5))　but　different　stability　were　prepared　by　using　microwave　electron　cyclotron　resonance　chemical　vapour　deposition　system　under　the　different　deposition　conditions.　It　was　proposed　that　there　was　no　direct　correlation　between　the　photosensitivity　and　the　hydrogen　content　(C-H)　as　well　as　H-Si　bonding　configurations,　but　for　the　stability,　they　were　the　critical　factors.　The　experimental　results　indicated　that　higher　substrate　temperature,　hydrogen　dilution　ratio　and　lower　deposition　rate　played　an　important　role　in　improving　the　microstructure　of　a-Si:H　films.　We　used　hydrogen　elimination　model　to　explain　our　experimental　results.