The present invention relates to a method for estimating an optimized transmission bit rate in a wireless local area network (LAN) system, which is to provide an accurate data transmission bit rate according to channel status when block data are transmitted in the wireless LAN system. According to the present invention, there is provided a method for estimating an optimized transmission bit rate according to the status of a data transmission bit rate in a wireless LAN system, comprising the steps of determining whether to change a current data transmission bit rate in a wireless LAN network; and estimating an optimized transmission bit rate on the basis of results of the determination in the determining step, and reflecting the estimated transmission bit rate upon transmission of data. The method is effective in that when data blocks are transmitted in the wireless LAN system, the performance degradation of data transmission invited due to an inappropriate selection of a transmission bit rate can be reduced.