<style type="text/css">
    table {
        border-collapse: collapse;
    }
    #one td {
        border: 1px solid #ff0000; 
    }
</style>

<table>
    <tr id="one">
        <td></td>
        <td></td>
    </tr>
    <tr id="two">
        <td></td>
        <td></td>
    </tr>
</table>

@Quang-Phu said in How to use border-color and border-collapse in html table?:

it seem border-color and border-collapse don't work on qml?

The documentation (https://doc.qt.io/qt-5/qml-qtquick-text.html ) says, "Note that the Supported HTML Subset is limited." The supported tags are listed at https://doc.qt.io/qt-5/richtext-html-subset. border-color and border-collapse are not supported.

EDIT: border-color and border-collapse are supported in Qt, but they are CSS properties, not HTML attributes. They must be placed in a stylesheet or the style attribute.

If you want a full-fledged HTML renderer, you must use a web engine like https://doc.qt.io/qt-5/qml-qtwebengine-webengineview.html