angularjs-ng-style

When i use Angular to dynamic change div 's backgroundImage , i find there are two ways to set backgrond-image: first: <div style="background:url({{example_expression}})"></div> the second: <div ng-style="{backgroundImage: 'url({{example_expression}})'}"></div> But when i change example_expression , only the first way can dynamically change the backgroundImage. There is a example in Plunker What's wrong with ngStyle? ng-style should not contain {{}} interpolation directive, you could directly access scope variable there. Also backgroundImage should be 'background-image' Markup <div ng-style="{