Disclosed are a signal transmitting method by a BS and a discovery method by a terminal to perform a WLAN discovery. The signal transmitting method by the BS includes: collecting information including beacon transmission periods and beacon transmission time of one or more WLAN Access Points (APs) within a cell range of the BS; generating grouping information in which beacon transmission time of the WLAN APs is mapped to a time area divided according to a grouping level from a reference time by using the collected information; and transmitting the grouping information to one or more reception terminals within cell range of the BS. Further, the discovery method by the terminal includes: receiving grouping information in which beacon transmission time of one or more WLAN Access Points (APs) is mapped to a time area divided according to a grouping level from a reference time; and discovering a WLAN AP only during a time to which the beacon transmission time is mapped according to the grouping information. Accordingly, the terminal can energy-efficiently discover a WLAN.