Disclosed herein are an automatically-switchable network extension apparatus and a switching method thereof. An automatic connection mechanism is particularly introduced into the apparatus. Exemplarily, a random number scheme is used to generate a value to be a basis for configuring the apparatus functioned as a CO or CPE operational mode. Based on the value, the method is to perform a connection with the other network extension apparatus. According to the embodiment, a set of connection parameters and the randomly-generated value are generated after the apparatus is initialized. The apparatus may be configured as CO or CPE operational mode according to the value, and simultaneously detect the operational mode of the apparatus to be linked. The apparatus accomplishes the connection if the two apparatuses have different modes, or the value is generated again to perform the connection.