Provided is a method for reserving a propagation time by estimating a channel environment in a wireless personal area network. The method includes the steps of: a) measuring a propagation range to the reception station upon starting data transaction with the reception station; b) measuring an average Strength Signal (ARSS) for determining a final transfer speed upon checking a transfer speed corresponding to the propagation range to the measured reception station based on a pre-defined table; c) determining a final transfer speed based on the transfer speed corresponding to the propagation range to the reception station according to a result that the measured ARSS is compared with Upper Bound RSS (URSS) and Lower Bound RSS (LRSS); and d) reserving a next propagation time according to the determined final transfer speed.