If I want to make more clients to connect to me，can I broadcast udp pong message with my own address within the message making more client know my address？

Thanks~

Nothing that your broadcast can get outside of the network, so it's an internal mechanism. It's important to point out that this isn't a 'popup' message or anything visual. Rather, if you have a listener on that port, it will be received by it. What it does with that message is up to the client app.