FilteredElementCollector col = new FilteredElementCollector(this._uiapplication.ActiveUIDocument.Document)
.WhereElementIsNotElementType()
.OfCategory(BuiltInCategory.OST_RvtLinks);
foreach (Element element in col)
{
RevitLinkInstance link = (element as RevitLinkInstance);
if (link == null)
continue;
Parameter pLinkInstanceName = link.get_Parameter(BuiltInParameter.RVT_LINK_INSTANCE_NAME);
if (string.IsNullOrEmpty(pLinkInstanceName.Definition.Name))
continue;
string linkInstanceName = link.get_Parameter(pLinkInstanceName.Definition).AsString();
}