Aiming　at　the　low　absorption　coefficient　of　hydrogenated　microcrystalline　silicon　thin　films　(μC-Si　:　H)　and　needing　to　be　prepared　with　high　thickness,　high　deposition　rate　must　be　taken　into　account;　considering　the　important　influence　of　the　reaction　pressure　on　the　deposition　rate　and　crystalline　volume　fraction,　and　based　on　the　analysis　of　the　advantages　and　disadvantages　on　the　mono-pressure　method,　we　promote　the　two-step-pressure　method　to　prepare　μc-Si　:　H　films,　i.　e.　at　first,　in　order　to　decrease　the　thickness　of　incubation　layer　from　the　amorphous　phase　transition　to　crystalline　phase,　we　use　the　high　pressure　to　deposit　2　min,　and　then　the　low　pressure　to　deposit　18　min　to　improve　the　density　and　decrease　the　oxygen　content　of　the　film.　As　a　result,　the　high-quality　μc-Si　:　H　films　with　high　photosensitivity,　high　crystalline　volume　fraction　and　good　photostability　were　prepared.