可以用ChildElementEnumerator迭代器进行，示例代码如下：

Bentley.DgnPlatformNET.Elements.CellHeaderElement cellEle;
Bentley.DgnPlatformNET.Elements.ChildElementEnumerator childEnumer = new Bentley.DgnPlatformNET.Elements.ChildElementEnumerator(cellEle);

while (childEnumer.MoveNext())
{
    if (childEnumer.Current.ElementType == Bentley.DgnPlatformNET.MSElementType.Text)
    {
        Bentley.DgnPlatformNET.Elements.TagElement tagEleCell = (Bentley.DgnPlatformNET.Elements.TagElement)childEnumer.Current;
        //to do...
    }
}