Silicon　nitride　(SiNx)　thin　films　were　deposited　by　low　frequency　(LF)　plasma　enhanced　chemical　vapor　deposition　(PECVD)　technology.　By　systematic　variation　of　the　process　parameters,　e.g.　reactive　gas　flow　rate,　LF　power,　chamber　gas　pressure　and　substrate　temperature.　Influences　of　above　parameters　on　the　intrinsic　stress　of　SiNx　films　were　studied　and　analyzed　by　combining　with　the　measured　refractive　index　(RI),　density,　infrared　spectra　results　of　deposited　SiNx　films.　The　results　showed　that　intrinsic　stress　of　SiNx　film　was　roughly　proportional　to　film　density,　which　was　inversely　proportional　to　hydrogen　content　in　the　SiNx　film.　Substrate　temperature　during　deposition　was　the　most　important　factor　affecting　hydrogen　content　in　deposited　film　and,　accordingly,　the　density　and　intrinsic　stress　of　SiNx　film.