The　effects　of　boric　acid　and　ammonium　tungstate　on　the　microstructure　and　properties　of　chromium-free　insulating　coatings　for　grain-oriented　silicon　steel　were　studied.　It　is　shown　that　the　wettability　of　coating　solution　can　be　significantly　improved　by　the　properly　combined　additions　of　boric　acid　and　ammonium　tungstate　in　the　chromium-free　phosphate　coating　solution.　The　coating　surface　becomes　more　compact　and　smooth,　and　the　bonding　quality　between　the　insulating　coating　and　the　steel　substrate　is　better.　The　best　comprehensive　properties　can　be　obtained　in　the　steel　coated　with　the　solution　containing　2.0wt%　boric　acid　and　0.5wt%　ammonium　tungstate.　The　lamination　factor　is　98.2%,　the　core　loss　P17/50　is　1.155　W•kg-1,　the　magnetic　induction　intensity　B8　is　1.876　T　and　the　interlamination　resistance　is　19　366　Ω•mm2.　Furthermore,　the　improvements　of　the　moisture　resistance　of　coating　and　the　corrosion　resistance　of　grain-oriented　silicon　steel　can　also　be　observed.　©　2021,　Materials　Review　Magazine.　All　right　reserved.