The　iron　Buddha　in　Fuzhou　Kaiyuan　Temple　is　one　of　the　biggest　ancient　ones,　existing　both　at　home　and　abroad.　In　this　paper,　the　construction　of　cast　object,　the　state　of　inner　surface,　the　chaplets　with　their　affected　zones,　the　gridding　stripes,　the　metallographic　structure,　and　the　chemical　composition　were　exhaustively　characterized.　The　observation　illustrated　that　there　was　no　any　sign　of　cold　steam　existed　in　the　main　structure　of　the　iron　Buddha.　The　chemical　calculation　exhibited　that　the　carbon　equivalent　is　4.3%,　falls　into　eutectic　composition.　The　metallographic　analysis　displayed　that　there　is　white　cast　iron　on　the　surface,　but　mottled　cast　iron　in　the　substrate.　We　try　to　discuss　the　advantages,　causes　and　related　technologies　of　the　three　important　technological　characteristics　observed.　©　2023　Chinese　Mechanical　Engineering　Society.　All　rights　reserved.