Ho can I get value of p3:type in the given XML Node?

Given the tags, I'm assuming that you're using LINQ to XML[^] and the System.Xml.Linq namespace.

You just need an XNamespace for the URI of the p3 namespace, which you then use to create an XName for the attribute name.

For example:

var element = XElement.Parse(@"<image p3:type=""simple"" p3:href=""tcm:86-10894"" p3:title=""tpw-event-large-7"" xmlns:p3=""http://www.w3.org/1999/xlink""></image>");

XNamespace p3 = "http://www.w3.org/1999/xlink";
XName attributeName = p3 + "type";

string type = (string)element.Attribute(attributeName);
Console.WriteLine(type);