Studies　on　size　effect　of　plastic　hinge　of　RC　members　are　still　rare　at　the　present　stage.　This　paper　explores　the　development　and　failure　characteristics　of　plastic　hinge　of　pure　bending　section　and　analysis　relevant　mechanical　parameters　of　size　effect.　Measured　tests　data　show　that　plastic　hinge　equivalent　length　is　close　to　the　depth　of　beam　which　has　no　obvious　size　effect.　However,　plastic　rotation　capacity　of　plastic　hinge　has　a　significant　size　effect.　Plastic　rotation　capacity　decreases　with　section　size　increases　if　evaluate　it　based　on　ultimate　load　state,　and　increases　with　section　size　increases　if　evaluate　it　based　on　measured　max　load　state.　©　(2014)　Trans　Tech　Publications,　Switzerland.