A method for a new node to join an ad-hoc network is provided. The method includes two basic functions. When the new node is allowed to join the network, the indicating device of the node being joined generates an indication. When the new node joins the network, the indicating device of the new node also generates an indication. The method further includes two commands, the join-rejection command and the joined-rejection command, to cancel the join procedure when the indicating device of the new node and the node being joined do not indicate correspondingly. Accordingly, the method efficiently reduces the possibility of joining an unanticipated node.