A method for generating a prompt message for network connection conversion and a network system thereof are provided. The system can be a LAN with multiple access points (APs). The method is operated in a root AP. The root AP receives a connection conversion command from a user device, in which a target AP is designated. The root AP determines at least one AP that is available to be connected with the target AP based on an instant wireless signal strength there-between. After that, the target AP obtains at least one connection rates from the target AP to the root AP via the at least one available APs. The root AP generates a prompt message for connection conversion according to the connection rates. A topology map displayed on the user device can be used to indicate the available APs for the connection conversion.